array-iteration.js
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var bind = require('../internals/function-bind-context');
var IndexedObject = require('../internals/indexed-object');
var toObject = require('../internals/to-object');
var toLength = require('../internals/to-length');
var arraySpeciesCreate = require('../internals/array-species-create');
var push = [].push;
// `Array.prototype.{ forEach, map, filter, some, every, find, findIndex, filterOut }` methods implementation
var createMethod = function (TYPE) {
var IS_MAP = TYPE == 1;
var IS_FILTER = TYPE == 2;
var IS_SOME = TYPE == 3;
var IS_EVERY = TYPE == 4;
var IS_FIND_INDEX = TYPE == 6;
var IS_FILTER_OUT = TYPE == 7;
var NO_HOLES = TYPE == 5 || IS_FIND_INDEX;
return function ($this, callbackfn, that, specificCreate) {
var O = toObject($this);
var self = IndexedObject(O);
var boundFunction = bind(callbackfn, that, 3);
var length = toLength(self.length);
var index = 0;
var create = specificCreate || arraySpeciesCreate;
var target = IS_MAP ? create($this, length) : IS_FILTER || IS_FILTER_OUT ? create($this, 0) : undefined;
var value, result;
for (;length > index; index++) if (NO_HOLES || index in self) {
value = self[index];
result = boundFunction(value, index, O);
if (TYPE) {
if (IS_MAP) target[index] = result; // map
else if (result) switch (TYPE) {
case 3: return true; // some
case 5: return value; // find
case 6: return index; // findIndex
case 2: push.call(target, value); // filter
} else switch (TYPE) {
case 4: return false; // every
case 7: push.call(target, value); // filterOut
}
}
}
return IS_FIND_INDEX ? -1 : IS_SOME || IS_EVERY ? IS_EVERY : target;
};
};
module.exports = {
// `Array.prototype.forEach` method
// https://tc39.github.io/ecma262/#sec-array.prototype.foreach
forEach: createMethod(0),
// `Array.prototype.map` method
// https://tc39.github.io/ecma262/#sec-array.prototype.map
map: createMethod(1),
// `Array.prototype.filter` method
// https://tc39.github.io/ecma262/#sec-array.prototype.filter
filter: createMethod(2),
// `Array.prototype.some` method
// https://tc39.github.io/ecma262/#sec-array.prototype.some
some: createMethod(3),
// `Array.prototype.every` method
// https://tc39.github.io/ecma262/#sec-array.prototype.every
every: createMethod(4),
// `Array.prototype.find` method
// https://tc39.github.io/ecma262/#sec-array.prototype.find
find: createMethod(5),
// `Array.prototype.findIndex` method
// https://tc39.github.io/ecma262/#sec-array.prototype.findIndex
findIndex: createMethod(6),
// `Array.prototype.filterOut` method
// https://github.com/tc39/proposal-array-filtering
filterOut: createMethod(7)
};