Convert Object to String

JavaScript Convert Object to String.png

1.Object

[JavaScript]
/*** object.toString() always return [object Object] ***/
var obj = {x: 1, y: 2};
obj.toString();    //=> "[object Object]"

obj = {};
obj.toString();    //=> "[object Object]

2.Array

[JavaScript]
/*** join each item with ',' ***/
var arr = [1, 2, 3];
arr.toString();    //=>"1,2,3"

arr = [1];
arr.toString();    //=>"1"

arr = [];
arr.toString();    //=>""

3.Function

[JavaScript]
/*** 函数的toString()方法，返回这个函数的定义表示 ***/
var func = function (x) { return x + 1 };
func.toString();    //=> "function (x) { return x + 1 }"

4.Date

[JavaScript]
/*** Date的toString()方法，返回一个可读的日期和时间字符串 ***/
var dt = new Date();
dt.toString();    //=> "Sat Apr 14 2018 18:15:38 GMT+0800 (中国标准时间)"

5.RegExp

[JavaScript]
/*** RegExp类的toString()，返回正则表达式直接量的字符串 ***/
var reg = /\d+/g;
reg.toString();    //=> "/\d+/g"

实例1

[JavaScript]
//对象obj转换为string类型
var obj = {x: 1, y: 2};
obj.toString();  //=> "[object Object]"，原始值
------------------------------
//"+"运算符引发的类型转换
var obj = {x: 1, y: 2};
var num = 1 + obj;
console.log(num);  //=> "1[object Object]"

num = "1" + obj;
console.log(num);  //=> "1[object Object]"
------------------------------
//"=="运算符引发的类型转换
var obj = {x: 1, y: 2};
if("[object Object]" == obj){
    console.log("Equal");      //=> "Equal"
}else{
    console.log("Not Equal");
}

实例2

[JavaScript]
//数组arrj转换为string类型
var arr = [1, 2, 3];
arr.toString();  //=> "1,2,3"，原始值
-------------------------------
arr = [9];
arr.toString();  //=> "9"，原始值
-------------------------------
arr = [];
arr.toString();  //=> ""，原始值

*******************************************
***                  实例               ***
*******************************************
//"+"运算符引发的类型转换
var arr = [1];
var num = 1 + arr;
console.log(num);  //=> "11"
------------------------------
//"=="运算符引发的类型转换
var arr = [1];
if("1" == arr){
    console.log("Equal");      //=> "Equal"
}else{
    console.log("Not Equal");
}

if(1 == arr){
    console.log("Equal");      //=> "Equal"
}else{
    console.log("Not Equal");
}