6 ms·

yet another duct tape kind of feature, from people already too corrupted by js, that will be further abused and cause yet more duct tape features in ES7. this

by asdf99 11y ago

yet another duct tape kind of feature, from people already too corrupted by js, that will be further abused and cause yet more duct tape features in ES7. this is nothing but a more convoluted way of the pattern that sets a unique object as a unique value for comparison. well, it adds a label for easy debug. hooray.

weavie 11y ago
No, also symbol keys don't pollute for-in, Object.keys or Object.getOwnPropertyNames so they are effectively non-global.
- yoshuaw 11y ago
  As long as you don't use Symbol.for() that is - https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Symbol/for https://developer.mozilla.org/en-US/docs/Web/JavaScript/Refe... (I do think symbols are useful though, replied for correctness.)
  - carussell 11y ago
    Symbols created with `Symbol.for` don't pollute any of those things, either. let x = Symbol.for("omghax"); let foo = Object.create(null) foo[x] = 'bar'; Object.keys(foo).length // returns 0
    - gcb0 11y ago
      there was already a solution for that: .style in dom elements. it is a place where you dump style properties ad-nausea. Why not simply add a single new property to Object? It would do the very same thing, would not change the language. it would be readily available to all browsers if you just added that single new key in your logic as you already do with .style and others, and everyone would move on with their lives. I have to agree this is a duct tape by people thinking they know language design. Now i will have to wait until all browsers have this before i can use. and then i will still have to worry about older browsers (oh android, the IE6 of moment). Not to mention the time browser developers would waste actually improving things will be wasted on that syntax sugar.
pmontra 11y ago
Symbols are used all the time in Ruby (and a bunch of other languages), not as duct tape but as a very core feature of the language. Why should it be different in JavaScript? The most simple way to use them is to replace definitions like this one var north = 1; var south = 2; var east = 3; var west = 4; var direction1 = north; var direction2 = south; direction1 === direction2 ? "ops" : "ok"; The programmer is doing the work of the interprer/compiler here and make sure to pick unique values for all the constants that are going to be compared together. With symbols that becomes var north = new Symbol(); var south = new Symbol(); var east = new Symbol(); var west = new Symbol(); var direction1 = north; var direction2 = south; direction1 === direction2 ? "ops" : "ok"; which is an improvement even if it is (in a traditional JavaScript way) so much more verbose than Ruby's direction1 = :north direction2 = :south direction1 === direction2 ? "ops" : "ok" I just wish they'll add some syntactical sugar to do without that "new Symbol()" thing and create symbols as needed like Ruby does. Unfortunately, from https://developer.mozilla.org/en/docs/Web/JavaScript/Reference/Global_Objects/Symbol https://developer.mozilla.org/en/docs/Web/JavaScript/Referen... Symbols and JSON.stringify() Symbol-keyed properties will be completely ignored when using JSON.stringify(): JSON.stringify({[Symbol("foo")]: "foo"}); // '{}' We're going to manually serialize them when they leave the RAM.
- masklinn 11y ago
  The base use case for JS symbols is not the same as Ruby symbols: regular strings will work just fine for that.
- ahoge 11y ago
  N, E, S, W? I think you want an enum for that.
  - pmontra 11y ago
    It was an example of replacing constants with symbols when the value of the constant really doesn't matter. Purposely not fancy stuff. I understand the advantages of enums (among the others, their values are constrained) but does JS have enums?

by asdf99 11y ago

weavie 11y ago

No, also symbol keys don't pollute for-in, Object.keys or Object.getOwnPropertyNames so they are effectively non-global.

yoshuaw 11y ago
As long as you don't use Symbol.for() that is - https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Symbol/for https://developer.mozilla.org/en-US/docs/Web/JavaScript/Refe... (I do think symbols are useful though, replied for correctness.)
- carussell 11y ago
  Symbols created with `Symbol.for` don't pollute any of those things, either. let x = Symbol.for("omghax"); let foo = Object.create(null) foo[x] = 'bar'; Object.keys(foo).length // returns 0
  - gcb0 11y ago
    there was already a solution for that: .style in dom elements. it is a place where you dump style properties ad-nausea. Why not simply add a single new property to Object? It would do the very same thing, would not change the language. it would be readily available to all browsers if you just added that single new key in your logic as you already do with .style and others, and everyone would move on with their lives. I have to agree this is a duct tape by people thinking they know language design. Now i will have to wait until all browsers have this before i can use. and then i will still have to worry about older browsers (oh android, the IE6 of moment). Not to mention the time browser developers would waste actually improving things will be wasted on that syntax sugar.

pmontra 11y ago

Symbols are used all the time in Ruby (and a bunch of other languages), not as duct tape but as a very core feature of the language. Why should it be different in JavaScript? The most simple way to use them is to replace definitions like this one var north = 1; var south = 2; var east = 3; var west = 4; var direction1 = north; var direction2 = south; direction1 === direction2 ? "ops" : "ok"; The programmer is doing the work of the interprer/compiler here and make sure to pick unique values for all the constants that are going to be compared together. With symbols that becomes var north = new Symbol(); var south = new Symbol(); var east = new Symbol(); var west = new Symbol(); var direction1 = north; var direction2 = south; direction1 === direction2 ? "ops" : "ok"; which is an improvement even if it is (in a traditional JavaScript way) so much more verbose than Ruby's direction1 = :north direction2 = :south direction1 === direction2 ? "ops" : "ok" I just wish they'll add some syntactical sugar to do without that "new Symbol()" thing and create symbols as needed like Ruby does. Unfortunately, from https://developer.mozilla.org/en/docs/Web/JavaScript/Reference/Global_Objects/Symbol https://developer.mozilla.org/en/docs/Web/JavaScript/Referen... Symbols and JSON.stringify() Symbol-keyed properties will be completely ignored when using JSON.stringify(): JSON.stringify({[Symbol("foo")]: "foo"}); // '{}' We're going to manually serialize them when they leave the RAM.

masklinn 11y ago
The base use case for JS symbols is not the same as Ruby symbols: regular strings will work just fine for that.
ahoge 11y ago
N, E, S, W? I think you want an enum for that.
- pmontra 11y ago
  It was an example of replacing constants with symbols when the value of the constant really doesn't matter. Purposely not fancy stuff. I understand the advantages of enums (among the others, their values are constrained) but does JS have enums?