function foo(n) {
var result = [];
for (var i = 0; i < n; i++)
(function(j) { result.push(function() { return j; }); })(i);
return result;
}
// new Array(n) could just be [] in all examples
//
// using Array.prototype.map
// sadly you can't do new Array(n).map
// because it doesn't iterate over undefined functions
function foo(n) {
for (var ret = new Array(n), i = 0; i < n; ++i) {
ret[i] = i;
}
return ret.map(function(_,n) { return function() { return n; }; });
}
// using Function.prototype.bind in a couple ways
function foo(n) {
function num() { return +this; }
for (var ret = new Array(n), i = 0; i < n; ++i) {
ret[i] = num.bind(i);
}
return ret;
}
function foo(n) {
function num(a) { return a; }
for (var ret = new Array(n), i = 0; i < n; ++i) {
ret[i] = num.bind(null, i); // could bind this to pretty much whatever here
}
return ret;
} function foo(a){
return Array.apply(0, new Array(a)).map(function(_, b){
return Number.bind(null, b)
});
} foo = (n) -> (-> i) for i in [0..n]Here's one way:
foo = (n) -> ((a) -> a).bind(null, i) for i in [0...n]
foo = (n) -> (-> +@).bind i for i in [0...n]How is `bind` still using a closure? `bind` just allows users to alter a function's execution context. However, the implementation varies according to the JS engine. Some of them may use a closure internally as a part of the process, but I don't think V8 does.