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The toString () method is invoked first when the date object is converted to a basic type. and Object calls toString () first when converted to a string
forexample one:
let date = new Date()
console.log(date.toString()); ／／Sun Dec 09 2018 16:48:43 GMT+0800 (中国标准时间)
console.log(date.valueOf()); ／／1544345323377
console.log(date + '5'); //Sun Dec 09 2018 16:48:43 GMT+0800 (中国标准时间)4
forexample two:
let date = {name: 'yjh'}
console.log(date.toString()); ／／[object Object]
console.log(date.valueOf()); ／／{name: "yjh"}
console.log(date + '5'); ／／[object Object]5
Your mistake：
对象在转换基本类型时，首先会调用 valueOf 然后调用 toString。
The toString () method is invoked first when the date object is converted to a basic type. and Object calls toString () first when converted to a string
forexample one: let date = new Date() console.log(date.toString()); ／／Sun Dec 09 2018 16:48:43 GMT+0800 (中国标准时间) console.log(date.valueOf()); ／／1544345323377
forexample two: let date = {name: 'yjh'} console.log(date.toString()); ／／[object Object] console.log(date.valueOf()); ／／{name: "yjh"}
Your mistake： 对象在转换基本类型时，首先会调用 valueOf 然后调用 toString。