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Array.prototype.filter #12
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Array.prototype.filter = function(callback, thisArg) {
if (this == undefined) {
throw new TypeError('this is null or not undefined');
}
if (typeof callback !== 'function') {
throw new TypeError(callback + 'is not a function');
}
const res = [];
// 让O成为回调函数的对象传递(强制转换对象)
const O = Object(this);
// >>>0 保证len为number,且为正整数
const len = O.length >>> 0;
for (let i = 0; i < len; i++) {
// 检查i是否在O的属性(会检查原型链)
if (i in O) {
// 回调函数调用传参
if (callback.call(thisArg, O[i], i, O)) {
res.push(O[i]);
}
}
}
return res;
} |
Array.prototype.filter = function (callback) {
const res = [];
for (let i = 0; i < this.length; i++) {
callback(this[i], i, this) && res.push(this[i]);
}
return res;
}; |
Array.prototype.filter = function(callback, thisArg) {
var result = [];
for (var i = 0; i < this.length; i++) {
if (callback.call(thisArg, this[i], i, this)) {
result.push(this[i]);
}
}
return result;
} |
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