js 隐式转换

	//String
    console.log(String(0)); //"0"
    console.log(String(1)); //"1"
    console.log(String(-1)); //"-1"
    console.log(String(true)); //"true"
    console.log(String(false)); //"false"
    console.log(String(null)); //"null"
    console.log(String(undefined)); //"undefined"
    console.log(String({})); //"[object Object]"
    console.log(String([])); //""
    console.log(String([1,2,3])); //"1,2,3"

    //Number
    console.log(Number("")); //0
    console.log(Number("0")); //0
    console.log(Number("1aw")); //NaN
    console.log(Number(true)); //1
    console.log(Number(false)); //0
    console.log(Number(null)); //0
    console.log(Number(undefined)); //NaN
    console.log(Number({})); //NaN
    console.log(Number([])); //0
    console.log(Number([1,2,3])); //NaN

    //Boolean
    console.log(Boolean(null)); //false
    console.log(Boolean(undefined)); //false
    console.log(Boolean("0")); //true
    console.log(Boolean("")); //false
    console.log(Boolean(1)); //true
    console.log(Boolean(-0)); //false
    console.log(Boolean(+0)); //false
    console.log(Boolean(0)); //false
    console.log(Boolean([])); //true
    console.log(Boolean([1,2,3])); //true
    console.log(Boolean({})); //true