为了在JavaScript中复制数组:下面哪个使用更快?
片的方法
var dup_array = original_array.slice();
For循环
for(var i = 0, len = original_array.length; i < len; ++i)
dup_array[i] = original_array[i];
我知道这两种方法都只做一个浅拷贝:如果original_array包含对对象的引用，对象将不会被克隆，但只有引用将被复制，因此两个数组将有对相同对象的引用。 但这不是问题的关键。
我只是在问速度。
当前回答
看看:link。重点不是速度，而是舒适度。此外，正如你所看到的，你只能在原始类型上使用slice(0)。
要制作数组的独立副本，而不是对其引用的副本，可以使用数组切片方法。
例子:
To make an independent copy of an array rather than a copy of the refence to it, you can use the array slice method. var oldArray = ["mip", "map", "mop"]; var newArray = oldArray.slice(); To copy or clone an object : function cloneObject(source) { for (i in source) { if (typeof source[i] == 'source') { this[i] = new cloneObject(source[i]); } else{ this[i] = source[i]; } } } var obj1= {bla:'blabla',foo:'foofoo',etc:'etc'}; var obj2= new cloneObject(obj1);
来源:链接
其他回答
看看:link。重点不是速度，而是舒适度。此外，正如你所看到的，你只能在原始类型上使用slice(0)。
要制作数组的独立副本，而不是对其引用的副本，可以使用数组切片方法。
例子:
To make an independent copy of an array rather than a copy of the refence to it, you can use the array slice method. var oldArray = ["mip", "map", "mop"]; var newArray = oldArray.slice(); To copy or clone an object : function cloneObject(source) { for (i in source) { if (typeof source[i] == 'source') { this[i] = new cloneObject(source[i]); } else{ this[i] = source[i]; } } } var obj1= {bla:'blabla',foo:'foofoo',etc:'etc'}; var obj2= new cloneObject(obj1);
来源:链接
深度克隆数组或对象的最简单方法:
var dup_array = JSON.parse(JSON.stringify(original_array))
基准时间!
function log(data) { document.getElementById("log").textContent += data + "\n"; } benchmark = (() => { time_function = function(ms, f, num) { var z = 0; var t = new Date().getTime(); for (z = 0; ((new Date().getTime() - t) < ms); z++) f(num); return (z) } function clone1(arr) { return arr.slice(0); } function clone2(arr) { return [...arr] } function clone3(arr) { return [].concat(arr); } Array.prototype.clone = function() { return this.map(e => Array.isArray(e) ? e.clone() : e); }; function clone4(arr) { return arr.clone(); } function benchmark() { function compare(a, b) { if (a[1] > b[1]) { return -1; } if (a[1] < b[1]) { return 1; } return 0; } funcs = [clone1, clone2, clone3, clone4]; results = []; funcs.forEach((ff) => { console.log("Benchmarking: " + ff.name); var s = time_function(2500, ff, Array(1024)); results.push([ff, s]); console.log("Score: " + s); }) return results.sort(compare); } return benchmark; })() log("Starting benchmark...\n"); res = benchmark(); console.log("Winner: " + res[0][0].name + " !!!"); count = 1; res.forEach((r) => { log((count++) + ". " + r[0].name + " score: " + Math.floor(10000 * r[1] / res[0][1]) / 100 + ((count == 2) ? "% *winner*" : "% speed of winner.") + " (" + Math.round(r[1] * 100) / 100 + ")"); }); log("\nWinner code:\n"); log(res[0][0].toString()); <textarea rows="50" cols="80" style="font-size: 16; resize:none; border: none;" id="log"></textarea>
自单击按钮以来，基准测试将运行10秒。
我的结果:
Chrome (V8引擎):
1. clone1 score: 100% *winner* (4110764)
2. clone3 score: 74.32% speed of winner. (3055225)
3. clone2 score: 30.75% speed of winner. (1264182)
4. clone4 score: 21.96% speed of winner. (902929)
Firefox (SpiderMonkey Engine):
1. clone1 score: 100% *winner* (8448353)
2. clone3 score: 16.44% speed of winner. (1389241)
3. clone4 score: 5.69% speed of winner. (481162)
4. clone2 score: 2.27% speed of winner. (192433)
赢家代码:
function clone1(arr) {
return arr.slice(0);
}
赢家引擎: SpiderMonkey (Mozilla Firefox)
var cloned_array = [].concat(target_array);
您可以遵循这段代码。不可变方式数组克隆。这是克隆数组的最佳方法
const array = [1, 2, 3, 4]
const newArray = [...array]
newArray.push(6)
console.log(array)
console.log(newArray)
