How to perform implicit conversion in JS

ToPrimitive Method ： This is a JS The method implicit in each value in the , Used to set the value （ Whether it's a basic type value or an object ） Convert to basic type value

If the value is a basic type , Then directly return the value itself ; If the value is an object , It probably looks like this ：

ToPrimitive（obj,type）
obj–> Objects that need to be transformed
type–> Expected result type

type The value of can be number perhaps string, The default is number

1） When type by number The rules of time are as follows ：

• call obj Of valueof Method , If it's the original value , Then return to , Otherwise, the next step
• call obj Of toString Method , If it's the original value , Then return to , Otherwise, the next step
• Throw out typeError abnormal

2） When type by string The rules of tense are as follows ：

• call obj Of toString Method , If it's the original value , Then return to , Otherwise, the next step
• call obj Of valueOf Method , If it's the original value , Then return to , Otherwise, the next step
• Throw out typeError abnormal

var objToNumber=function(value){
    
            return Number(value.valueOf().toString())
        }
        console.log(objToNumber('')===0);//true
        console.log(objToNumber({
    })===NaN);//false

1. + There is only one on either side of the operator string When type variable , Variables on both sides will be implicitly converted to strings ; In other cases, both variables will be converted to numbers

        console.log(1+'23');//123
        console.log(1+false);//1
        console.log('1'+false);//1false
        console.log(true+false);//1

2. -、*、/ The operands are converted to numbers

        console.log(20-'5');//15
        console.log(1*false);//0
        console.log(1/'aa');//NaN

3. ==, Cast data types , Equivalent unequal type
4. about < and > Comparison symbol , Compare in alphabetical order

        console.log('a'>'b');//false
        console.log('aa'<'bc');//true

5. In other cases , Convert to numbers and compare

        console.log(12<'13');//true
        console.log(false<-1);//false

6. object

        var a={
    }
        console.log(a>2);//false