Array.from is a good addition, I guess any good framework has it.
Though, `Array.of` in contrast doesn't bring much of a sugar. Compare
these two apples-to-apples:
Array.of( "things", "that", "aren't", "currently", "an", "array" )
vs.
["things", "that", "aren't", "currently", "an", "array"]
what's the goal in first case to write this useless "Array.of" prefix
and exactly the same to manually enumerate the items? In fact, the
second one is more suggared than the first one (the first one is: "added
useless prefix Array.of and brackets around items are replaced with call
parens").
Another thing to consider is `Array.prototype.fill` method which we
discussed before.
The problem:
Array(4).map(function(x) x * x); // [NaN, NaN, NaN, NaN]
(by the way, this mistaken example is still mentioned in this document
http://wiki.ecmascript.org/doku.php?id=strawman:shorter_function_syntax,
in the "Alternate Syntax Proposals" section, though, is fixed in the
main section with `let randomArray =
NonHoleyArray(10).map(#{Math.random()});` when was mentioned before).
The solution:
// fill with a simple value
Array(4).fill(true); // [true, true, true, true]
// fill with a function in needed context of this
let object = {data: 4};
Array(3).fill(-> if this.data > 3 { 'accepted' } else {'declined' },
object);
Implementation is quite simple also, though, can be optimized in built-ins:
Array.prototype.fill || Object.defineProperty(Array.prototype, "fill", {
valu: function arrayFill(filler) {
for (var k = 0; k < this.length; k++) {
this[k] = typeof filler == "function" ? filler.call(thisArg ||
this, this[k], k, this) : value;
}
return this;
},
configurable: true,
writable: true
});
Also class-method Array.fill(count, filler) can be considered.
Dmitry.
On 10.07.2011 9:35, Brendan Eich wrote:
Thanks to @rwaldron for compiling these, and dherman
(@littlecalculist) for being a twitter conversationalist who speaks in
JS:
https://gist.github.com/1074126
http://jsfiddle.net/rwaldron/5UjWy/
From a twitter conversation sparked by an IRC conversation where I
reminded [email protected] <mailto:[email protected]> that ES5
Function.prototype.bind can be used to spread arguments into a 'new'
expression.
Standardizing these would save reinventing them, and the built-ins
could be optimized quite a bit.
/be
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