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]