js数组直接赋值的问题(js数组的浅拷贝与深拷贝方法)

var a =[1,2,3];
var b=a;
a[0]=30;
console.log(a,b);

//结果： [30, 2, 3]   [30, 2, 3]

var a=[1,2,3];
var b=[].concat(a); 
a[0]=30;
console.log(a,b);

//结果：[30, 2, 3]  [1, 2, 3]

var a=[1,2,3];
var b=[].concat(a); 
var c=[...a]; 
a[0]=30;
console.log(a,b,c);

//结果：[30, 2, 3]  [1, 2, 3] [1, 2, 3]

let arr1=[1,2,3];
var newArr4 = arr1.join(" ").split(" ").map(function(i){
    return parseInt(i);
    
}); 
arr1[0]=30;
console.log(arr1,newArr4);

//VM1175:1 (3) [30, 2, 3] (3) [1, 2, 3]

let arr=[{a:1,b:2},{a:3,b:4}]; 
let arr1=JSON.parse(JSON.stringify(arr)); 
arr[0].a=10;
console.log(arr,arr1); 

//输出结果如下
(2) [{…}, {…}]
    0: {a: 10, b: 2}
    1: {a: 3, b: 4}

(2) [{…}, {…}]
    0: {a: 1, b: 2}
    1: {a: 3, b: 4}

let arr=[{a:1,b:2},{a:3,b:4}]; 
let arr1=$.extend(true,[],arr); 
arr[0].a=10;
console.log(arr,arr1); 

//输出结果如下
(2) [{…}, {…}]
    0: {a: 10, b: 2}
    1: {a: 3, b: 4}
    
(2) [{…}, {…}, contains: ƒ, each: ƒ, uniquelize: ƒ]
    0: {a: 1, b: 2}
    1: {a: 3, b: 4}