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 it could be used like this:if ( a == 1 ||= 2 ||=3 ||=5) { //do something if a is either 1,2,3,5} and it could be used like thisa || = 0// a = a || 0thanks _______________________________________________ es-discuss mailing list [hidden email] https://mail.mozilla.org/listinfo/es-discuss
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 `a ||= b` looks like an in-place logical or, like `+=`.`a = a || b` would have very different semantics to that which you propose.In Python this would be written:```pythonif a in [1, 2, 3, 5]:    # stuff```In JS we have similar but slightly less semantic:```jsif ([1, 2, 3, 5].indexOf(a) > -1) {    // stuff}```On Sunday, August 9, 2015, <[hidden email]> wrote:it could be used like this:if ( a == 1 ||= 2 ||=3 ||=5) { //do something if a is either 1,2,3,5} and it could be used like thisa || = 0// a = a || 0thanks _______________________________________________ es-discuss mailing list [hidden email] https://mail.mozilla.org/listinfo/es-discuss
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 In reply to this post by myemailum14 I was going to suggest a Set, now that ECMA has them… http://www.ecma-international.org/ecma-262/6.0/index.html#sec-set-objects```jsif ((new Set([1,2,3,5]).has(a)) {    // stuff}```On Sun, Aug 9, 2015 at 4:20 PM <[hidden email]> wrote:it could be used like this:if ( a == 1 ||= 2 ||=3 ||=5) { //do something if a is either 1,2,3,5} and it could be used like thisa || = 0// a = a || 0thanks _______________________________________________ es-discuss mailing list [hidden email] https://mail.mozilla.org/listinfo/es-discuss _______________________________________________ es-discuss mailing list [hidden email] https://mail.mozilla.org/listinfo/es-discuss
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 Or, there is the likely ES7 Array#contains for comparing multiple numbers. ```js [1, 2, 3].contains(value); ``` As for the operator proposed here, there's already an existing proposal for a safer version which doesn't coerce: http://wiki.ecmascript.org/doku.php?id=strawman:default_operator. On Sun, Aug 9, 2015, 19:02 Michael A. Smith <[hidden email]> wrote:I was going to suggest a Set, now that ECMA has them… http://www.ecma-international.org/ecma-262/6.0/index.html#sec-set-objects```jsif ((new Set([1,2,3,5]).has(a)) {    // stuff}```On Sun, Aug 9, 2015 at 4:20 PM <[hidden email]> wrote:it could be used like this:if ( a == 1 ||= 2 ||=3 ||=5) { //do something if a is either 1,2,3,5} and it could be used like thisa || = 0// a = a || 0thanks _______________________________________________ es-discuss mailing list [hidden email] https://mail.mozilla.org/listinfo/es-discuss _______________________________________________ es-discuss mailing list [hidden email] https://mail.mozilla.org/listinfo/es-discuss _______________________________________________ es-discuss mailing list [hidden email] https://mail.mozilla.org/listinfo/es-discuss
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 why create an array when there can be an operator. I think if we do survey people will like this, ||=, it's more expressive.On Sun, Aug 9, 2015 at 9:41 PM, Isiah Meadows wrote:Or, there is the likely ES7 Array#contains for comparing multiple numbers. ```js [1, 2, 3].contains(value); ``` As for the operator proposed here, there's already an existing proposal for a safer version which doesn't coerce: http://wiki.ecmascript.org/doku.php?id=strawman:default_operator. On Sun, Aug 9, 2015, 19:02 Michael A. Smith <[hidden email]> wrote:I was going to suggest a Set, now that ECMA has them… http://www.ecma-international.org/ecma-262/6.0/index.html#sec-set-objects```jsif ((new Set([1,2,3,5]).has(a)) {    // stuff}```On Sun, Aug 9, 2015 at 4:20 PM <[hidden email]> wrote:it could be used like this:if ( a == 1 ||= 2 ||=3 ||=5) { //do something if a is either 1,2,3,5} and it could be used like thisa || = 0// a = a || 0thanks _______________________________________________ es-discuss mailing list [hidden email] https://mail.mozilla.org/listinfo/es-discuss _______________________________________________ es-discuss mailing list [hidden email] https://mail.mozilla.org/listinfo/es-discuss _______________________________________________ es-discuss mailing list [hidden email] https://mail.mozilla.org/listinfo/es-discuss
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 Isn't prop ||= 0;better than prop = prop || 0;and it can be even defined like this.prop ||= var1 ||= var2 ||= 0;but then i dont know how we can use it ike thisif (num == 3 ||=4 ||=6)On Sun, Aug 9, 2015 at 9:47 PM, wrote:why create an array when there can be an operator. I think if we do survey people will like this, ||=, it's more expressive.On Sun, Aug 9, 2015 at 9:41 PM, Isiah Meadows wrote:Or, there is the likely ES7 Array#contains for comparing multiple numbers. ```js [1, 2, 3].contains(value); ``` As for the operator proposed here, there's already an existing proposal for a safer version which doesn't coerce: http://wiki.ecmascript.org/doku.php?id=strawman:default_operator. On Sun, Aug 9, 2015, 19:02 Michael A. Smith <[hidden email]> wrote:I was going to suggest a Set, now that ECMA has them… http://www.ecma-international.org/ecma-262/6.0/index.html#sec-set-objects```jsif ((new Set([1,2,3,5]).has(a)) {    // stuff}```On Sun, Aug 9, 2015 at 4:20 PM <[hidden email]> wrote:it could be used like this:if ( a == 1 ||= 2 ||=3 ||=5) { //do something if a is either 1,2,3,5} and it could be used like thisa || = 0// a = a || 0thanks _______________________________________________ es-discuss mailing list [hidden email] https://mail.mozilla.org/listinfo/es-discuss _______________________________________________ es-discuss mailing list [hidden email] https://mail.mozilla.org/listinfo/es-discuss _______________________________________________ es-discuss mailing list [hidden email] https://mail.mozilla.org/listinfo/es-discuss
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 In reply to this post by Isiah Meadows-2 fwiw, just like String#includes, "contains" has been renamed to Array#includes (see https://github.com/tc39/Array.prototype.includes/)On Sun, Aug 9, 2015 at 8:41 PM, Isiah Meadows wrote:Or, there is the likely ES7 Array#contains for comparing multiple numbers. ```js [1, 2, 3].contains(value); ``` As for the operator proposed here, there's already an existing proposal for a safer version which doesn't coerce: http://wiki.ecmascript.org/doku.php?id=strawman:default_operator. On Sun, Aug 9, 2015, 19:02 Michael A. Smith <[hidden email]> wrote:I was going to suggest a Set, now that ECMA has them… http://www.ecma-international.org/ecma-262/6.0/index.html#sec-set-objects```jsif ((new Set([1,2,3,5]).has(a)) {    // stuff}```On Sun, Aug 9, 2015 at 4:20 PM <[hidden email]> wrote:it could be used like this:if ( a == 1 ||= 2 ||=3 ||=5) { //do something if a is either 1,2,3,5} and it could be used like thisa || = 0// a = a || 0thanks _______________________________________________ es-discuss mailing list [hidden email] https://mail.mozilla.org/listinfo/es-discuss _______________________________________________ es-discuss mailing list [hidden email] https://mail.mozilla.org/listinfo/es-discuss _______________________________________________ es-discuss mailing list [hidden email] https://mail.mozilla.org/listinfo/es-discuss _______________________________________________ es-discuss mailing list [hidden email] https://mail.mozilla.org/listinfo/es-discuss
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 In reply to this post by myemailum14 On Mon, Aug 10, 2015 at 3:50 AM,  <[hidden email]> wrote: > Isn't > prop ||= 0; > better than > prop = prop || 0; > and it can be even defined like this. > prop ||= var1 ||= var2 ||= 0; > but then i dont know how we can use it ike this > if (num == 3 ||=4 ||=6) Sounds like you want two operators; `||=` for the compound assignment case and `||==` and `||===` for the "compare the RHS to the LHS of the last `===` or `==` op", or something like that. Defining a single op for both of these cases is likely to lead to ambiguity. The `||=` (and `&&=`) case has been discussed a couple of times, look in the esdiscuss archives. I'm sure something like `||==` has been discussed too though I don't recall it myself. I tend to use switches myself for this in case perf is an issue. - peter _______________________________________________ es-discuss mailing list [hidden email] https://mail.mozilla.org/listinfo/es-discuss
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 Thanks I'll be searching through archive, and yea i think this is something very simple and yet innovative.On Mon, Aug 10, 2015 at 3:55 AM, Peter van der Zee wrote:On Mon, Aug 10, 2015 at 3:50 AM,  <[hidden email]> wrote: > Isn't > prop ||= 0; > better than > prop = prop || 0; > and it can be even defined like this. > prop ||= var1 ||= var2 ||= 0; > but then i dont know how we can use it ike this > if (num == 3 ||=4 ||=6) Sounds like you want two operators; `||=` for the compound assignment case and `||==` and `||===` for the "compare the RHS to the LHS of the last `===` or `==` op", or something like that. Defining a single op for both of these cases is likely to lead to ambiguity. The `||=` (and `&&=`) case has been discussed a couple of times, look in the esdiscuss archives. I'm sure something like `||==` has been discussed too though I don't recall it myself. I tend to use switches myself for this in case perf is an issue. - peter _______________________________________________ es-discuss mailing list [hidden email] https://mail.mozilla.org/listinfo/es-discuss
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 Isn't this what switch statements are for?  Perhaps a condensed operator version of a switch would be useful?    if (a == 0 : 1 : 2) {    }Or perhaps something similar to the set version, but without the set:    if (a of 1, 2, 3, 4, 5, 6) {    }One could do this as a standard lib variadic function, I suppose:    if (select(a, 1, 2, 3, 4, 5, 6)) {    }Cheers,JoeOn Mon, Aug 10, 2015 at 6:09 AM, wrote:Thanks I'll be searching through archive, and yea i think this is something very simple and yet innovative.On Mon, Aug 10, 2015 at 3:55 AM, Peter van der Zee wrote:On Mon, Aug 10, 2015 at 3:50 AM,  <[hidden email]> wrote: > Isn't > prop ||= 0; > better than > prop = prop || 0; > and it can be even defined like this. > prop ||= var1 ||= var2 ||= 0; > but then i dont know how we can use it ike this > if (num == 3 ||=4 ||=6) Sounds like you want two operators; `||=` for the compound assignment case and `||==` and `||===` for the "compare the RHS to the LHS of the last `===` or `==` op", or something like that. Defining a single op for both of these cases is likely to lead to ambiguity. The `||=` (and `&&=`) case has been discussed a couple of times, look in the esdiscuss archives. I'm sure something like `||==` has been discussed too though I don't recall it myself. I tend to use switches myself for this in case perf is an issue. - peter _______________________________________________ es-discuss mailing list [hidden email] https://mail.mozilla.org/listinfo/es-discuss _______________________________________________ es-discuss mailing list [hidden email] https://mail.mozilla.org/listinfo/es-discuss
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 On Mon, Aug 10, 2015 at 5:42 PM, joe wrote:Isn't this what switch statements are for?  Perhaps a condensed operator version of a switch would be useful?    if (a == 0 : 1 : 2) {    }switch does eqeqeq comparison so is not exactly the same`switch(1) { case true: console.log('never'); }` Or perhaps something similar to the set version, but without the set:    if (a of 1, 2, 3, 4, 5, 6) {    }an `if/of` doesn't feel that right to me ... weird semantic`[1, 2, 3, 4, 5, 6].contains(a)` looks better ? One could do this as a standard lib variadic function, I suppose:    if (select(a, 1, 2, 3, 4, 5, 6)) {    }No, the main  point of having operators is that the engine could just skip the fallback part.`var a = 1 || doSomethingComplex(123)`as example, will never execute doSomethingComplex whilc passing any value as argument should be already resolved as value.In any case, FWIW, I think this is a classic "nostalgia operator" asked from someone that uses from another PL or just started using JS ... I wouldn't mind some well integrated and well thought shortcut, but I feel like this should be the least priority for ES.nextBest Regards Cheers,JoeOn Mon, Aug 10, 2015 at 6:09 AM, wrote:Thanks I'll be searching through archive, and yea i think this is something very simple and yet innovative.On Mon, Aug 10, 2015 at 3:55 AM, Peter van der Zee wrote:On Mon, Aug 10, 2015 at 3:50 AM,  <[hidden email]> wrote: > Isn't > prop ||= 0; > better than > prop = prop || 0; > and it can be even defined like this. > prop ||= var1 ||= var2 ||= 0; > but then i dont know how we can use it ike this > if (num == 3 ||=4 ||=6) Sounds like you want two operators; `||=` for the compound assignment case and `||==` and `||===` for the "compare the RHS to the LHS of the last `===` or `==` op", or something like that. Defining a single op for both of these cases is likely to lead to ambiguity. The `||=` (and `&&=`) case has been discussed a couple of times, look in the esdiscuss archives. I'm sure something like `||==` has been discussed too though I don't recall it myself. I tend to use switches myself for this in case perf is an issue. - peter _______________________________________________ es-discuss mailing list [hidden email] https://mail.mozilla.org/listinfo/es-discuss _______________________________________________ es-discuss mailing list [hidden email] https://mail.mozilla.org/listinfo/es-discuss _______________________________________________ es-discuss mailing list [hidden email] https://mail.mozilla.org/listinfo/es-discuss
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 I actually like `[1, 2, 3, 4, 5, 6].contains(a)` better, too.  The question is, will engines actually optimize it.  I have to admit, I don't trust people who say VMs or compilers will do the optimizing for you.  I've had to track down vendor keywords to force C/C++ compilers to inline functions more than once, after the idiot thing's optimizers failed to do so, not even when I was using the inline keyword (which is an optimization hint, not an imperative).I have never had this happen with only one compiler, either; if gcc won't inline a function, msvc won't either.Instead of saying "the VMs probably will. . ." perhaps the TC39 committee should *mandate* that they do so formally, in the spec.  Then people like me could stop violating bits of the standard that aren't workable with how today's VMs work, like the return value of .next methods in iterators.JoeOn Mon, Aug 10, 2015 at 9:52 AM, Andrea Giammarchi wrote:On Mon, Aug 10, 2015 at 5:42 PM, joe wrote:Isn't this what switch statements are for?  Perhaps a condensed operator version of a switch would be useful?    if (a == 0 : 1 : 2) {    }switch does eqeqeq comparison so is not exactly the same`switch(1) { case true: console.log('never'); }` Or perhaps something similar to the set version, but without the set:    if (a of 1, 2, 3, 4, 5, 6) {    }an `if/of` doesn't feel that right to me ... weird semantic`[1, 2, 3, 4, 5, 6].contains(a)` looks better ? One could do this as a standard lib variadic function, I suppose:    if (select(a, 1, 2, 3, 4, 5, 6)) {    }No, the main  point of having operators is that the engine could just skip the fallback part.`var a = 1 || doSomethingComplex(123)`as example, will never execute doSomethingComplex whilc passing any value as argument should be already resolved as value.In any case, FWIW, I think this is a classic "nostalgia operator" asked from someone that uses from another PL or just started using JS ... I wouldn't mind some well integrated and well thought shortcut, but I feel like this should be the least priority for ES.nextBest Regards Cheers,JoeOn Mon, Aug 10, 2015 at 6:09 AM, wrote:Thanks I'll be searching through archive, and yea i think this is something very simple and yet innovative.On Mon, Aug 10, 2015 at 3:55 AM, Peter van der Zee wrote:On Mon, Aug 10, 2015 at 3:50 AM,  <[hidden email]> wrote: > Isn't > prop ||= 0; > better than > prop = prop || 0; > and it can be even defined like this. > prop ||= var1 ||= var2 ||= 0; > but then i dont know how we can use it ike this > if (num == 3 ||=4 ||=6) Sounds like you want two operators; `||=` for the compound assignment case and `||==` and `||===` for the "compare the RHS to the LHS of the last `===` or `==` op", or something like that. Defining a single op for both of these cases is likely to lead to ambiguity. The `||=` (and `&&=`) case has been discussed a couple of times, look in the esdiscuss archives. I'm sure something like `||==` has been discussed too though I don't recall it myself. I tend to use switches myself for this in case perf is an issue. - peter _______________________________________________ es-discuss mailing list [hidden email] https://mail.mozilla.org/listinfo/es-discuss _______________________________________________ es-discuss mailing list [hidden email] https://mail.mozilla.org/listinfo/es-discuss _______________________________________________ es-discuss mailing list [hidden email] https://mail.mozilla.org/listinfo/es-discuss
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 I one day writing js thought why there is no operator for ||= there should be syntax makes sense, then i learned some ruby and it had this already. Now i was convinced it makes sense afterall. On Mon, Aug 10, 2015 at 1:15 PM, joe wrote:I actually like `[1, 2, 3, 4, 5, 6].contains(a)` better, too.  The question is, will engines actually optimize it.  I have to admit, I don't trust people who say VMs or compilers will do the optimizing for you.  I've had to track down vendor keywords to force C/C++ compilers to inline functions more than once, after the idiot thing's optimizers failed to do so, not even when I was using the inline keyword (which is an optimization hint, not an imperative).I have never had this happen with only one compiler, either; if gcc won't inline a function, msvc won't either.Instead of saying "the VMs probably will. . ." perhaps the TC39 committee should *mandate* that they do so formally, in the spec.  Then people like me could stop violating bits of the standard that aren't workable with how today's VMs work, like the return value of .next methods in iterators.JoeOn Mon, Aug 10, 2015 at 9:52 AM, Andrea Giammarchi wrote:On Mon, Aug 10, 2015 at 5:42 PM, joe wrote:Isn't this what switch statements are for?  Perhaps a condensed operator version of a switch would be useful?    if (a == 0 : 1 : 2) {    }switch does eqeqeq comparison so is not exactly the same`switch(1) { case true: console.log('never'); }` Or perhaps something similar to the set version, but without the set:    if (a of 1, 2, 3, 4, 5, 6) {    }an `if/of` doesn't feel that right to me ... weird semantic`[1, 2, 3, 4, 5, 6].contains(a)` looks better ? One could do this as a standard lib variadic function, I suppose:    if (select(a, 1, 2, 3, 4, 5, 6)) {    }No, the main  point of having operators is that the engine could just skip the fallback part.`var a = 1 || doSomethingComplex(123)`as example, will never execute doSomethingComplex whilc passing any value as argument should be already resolved as value.In any case, FWIW, I think this is a classic "nostalgia operator" asked from someone that uses from another PL or just started using JS ... I wouldn't mind some well integrated and well thought shortcut, but I feel like this should be the least priority for ES.nextBest Regards Cheers,JoeOn Mon, Aug 10, 2015 at 6:09 AM, wrote:Thanks I'll be searching through archive, and yea i think this is something very simple and yet innovative.On Mon, Aug 10, 2015 at 3:55 AM, Peter van der Zee wrote:On Mon, Aug 10, 2015 at 3:50 AM,  <[hidden email]> wrote: > Isn't > prop ||= 0; > better than > prop = prop || 0; > and it can be even defined like this. > prop ||= var1 ||= var2 ||= 0; > but then i dont know how we can use it ike this > if (num == 3 ||=4 ||=6) Sounds like you want two operators; `||=` for the compound assignment case and `||==` and `||===` for the "compare the RHS to the LHS of the last `===` or `==` op", or something like that. Defining a single op for both of these cases is likely to lead to ambiguity. The `||=` (and `&&=`) case has been discussed a couple of times, look in the esdiscuss archives. I'm sure something like `||==` has been discussed too though I don't recall it myself. I tend to use switches myself for this in case perf is an issue. - peter _______________________________________________ es-discuss mailing list [hidden email] https://mail.mozilla.org/listinfo/es-discuss _______________________________________________ es-discuss mailing list [hidden email] https://mail.mozilla.org/listinfo/es-discuss _______________________________________________ es-discuss mailing list [hidden email] https://mail.mozilla.org/listinfo/es-discuss
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 In reply to this post by joe wellOn Mon, Aug 10, 2015 at 6:15 PM, joe wrote:I actually like `[1, 2, 3, 4, 5, 6].contains(a)` better, too.  The question is, will engines actually optimize it.if the entire environment never touches even "by accident" the `Array.prototype` I don't see why that couldn't be optimized by the engine ... but in general, if a *small* `Array#contains` is the performance  bottleneck of any application I think there's probably something else wrong there, or maybe the only better performance approach would be a `switch` with all cases well defined with a `break` (as someone somewhere suggested once about a speedy subset of JS) Regards _______________________________________________ es-discuss mailing list [hidden email] https://mail.mozilla.org/listinfo/es-discuss
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 In reply to this post by myemailum14 [hidden email] wrote: > I one day writing js thought why there is no operator for ||= there The problem with || (and, consequently, ||=) is that it uses ToBoolean. We have all used to it, but I'd bet what we mostly want is "if (x == null) ...", so I think ||= should NOT be added to the language and || used as value || anotherValue should be left to rot (as a boolean short-circuit in if/while it is, of course, indispensable); on the other hand, we should add something like value ?? anotherValue and lvalue ??= anotherValue, instead, which would only kick in case of null/undefined. > should be syntax makes sense, then i learned some ruby and it had this > already. Now i was convinced it makes sense afterall. _______________________________________________ es-discuss mailing list [hidden email] https://mail.mozilla.org/listinfo/es-discuss
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 In reply to this post by myemailum14 Please search for older proposals on ecmascript.org. You'd find http://wiki.ecmascript.org/doku.php?id=strawman:default_operatorES6 parameter default values took a look of wind out of this one's sails. /be [hidden email] wrote: > it could be used like this: > > if ( a == 1 ||= 2 ||=3 ||=5) { //do something if a is either 1,2,3,5} > > and it could be used like this > > a || = 0 > // a = a || 0 > > thanks > _______________________________________________ > es-discuss mailing list > [hidden email] > https://mail.mozilla.org/listinfo/es-discuss_______________________________________________ es-discuss mailing list [hidden email] https://mail.mozilla.org/listinfo/es-discuss
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 On Mon, Aug 10, 2015 at 1:53 PM, Brendan Eich <[hidden email]> wrote: > Please search for older proposals on ecmascript.org. You'd find > > http://wiki.ecmascript.org/doku.php?id=strawman:default_operator> > ES6 parameter default values took a look of wind out of this one's sails. You're pattern-matching incorrectly - this is not the default operator, it's "seeing if a var is any of several possible matches". But yeah, as Alexander said, Python gets by just fine by creating an array or tuple and asking about membership; using [].contains() should be just fine in JS too. ~TJ _______________________________________________ es-discuss mailing list [hidden email] https://mail.mozilla.org/listinfo/es-discuss
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