010 手写数组的 push、pop 方法 ?
CoderBin 1/28/2022 JS数组
参照 ecma262 草案的规定，关于 push 和 pop 的规范如下图所示:
首先来实现一下 push 方法:
Array.prototype.push = function(...items) {
let O = Object(this);
let len = this.length >>> 0;
let argCount = items.length >>> 0;
// 2 ** 53 - 1 为JS能表示的最大正整数
if (len + argCount > 2 ** 53 - 1) {
throw new TypeError("The number of array is over the max value restricted!")
}
for(let i = 0; i < argCount; i++) {
O[len + i] = items[i];
}
let newLength = len + argCount;
O.length = newLength;
return newLength;
}
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亲测已通过MDN上所有测试用例。MDN链接 (opens new window)
然后来实现 pop 方法:
Array.prototype.pop = function() {
let O = Object(this);
let len = this.length >>> 0;
if (len === 0) {
O.length = 0;
return undefined;
}
len --;
let value = O[len];
delete O[len];
O.length = len;
return value;
}
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亲测已通过MDN上所有测试用例。MDN链接 (opens new window)
参考链接: