JavaScript数组复制详解

前面的话  前面的博文中介绍了对象拷贝，本文将详细介绍数组复制pushfunctioncopyArr

前面的话

  前面的博文中介绍了对象拷贝，本文将详细介绍数组复制

push

function copyArray(arr){
 var result = [];
 for(var i = 0; i < arr.length; i++){
 result.push(arr[i]);
 }
 return result;
}

var obj1=[1,2,3];
var obj2=copyArray(obj1);
console.log(obj1); //[1,2,3]
console.log(obj2); //[1,2,3]
obj2.push(4);
console.log(obj1); //[1,2,3]
console.log(obj2); //[1,2,3,4]
 

join   使用该方法的缺点是数组中的项全部变成了字符串形式

function copyArray(arr){
 var result = [];
 result = arr.join().split(',');
 return result;
}

var obj1=[1,2,3];
var obj2=copyArray(obj1);
console.log(obj1); //[1,2,3]
console.log(obj2); //['1','2','3']
obj2.push(4);
console.log(obj1); //[1,2,3]
console.log(obj2); //['1','2','3',4]
 

concat

function copyArray(arr){
 var result = [];
 result = arr.concat();
 return result;
}

var obj1=[1,2,3];
var obj2=copyArray(obj1);
console.log(obj1); //[1,2,3]
console.log(obj2); //[1,2,3]
obj2.push(4);
console.log(obj1); //[1,2,3]
console.log(obj2); //[1,2,3,4]
 

slice

function copyArray(arr){
 var result = [];
 result = arr.slice();
 return result;
}

var obj1=[1,2,3];
var obj2=copyArray(obj1);
console.log(obj1); //[1,2,3]
console.log(obj2); //[1,2,3]
obj2.push(4);
console.log(obj1); //[1,2,3]
console.log(obj2); //[1,2,3,4]
 

深拷贝

  以上方法实现的仅是数组的浅拷贝，如果要实现数组的深拷贝，需要使用递归方法

function copyArray(arr,result){
 var result = result || [];
 for(var i = 0; i < arr.length; i++){
 if(arr[i] instanceof Array){
 result[i] = [];
 copyArray(arr[i],result[i]);
 }else{
 result[i] = arr[i];
 } 
 }
 return result;
}

var obj1=[1,2,[3,4]];
var obj2=copyArray(obj1);
console.log(obj1[2]); //[3,4]
console.log(obj2[2]); //[3,4]
obj2[2].push(5);
console.log(obj1[2]); //[3,4]
console.log(obj2[2]); //[3,4,5]