Javascript Boolean、Nnumber、String 强制类型转换的区别详细介绍

var b1 = Boolean("");//返回false,空字符串
var b2 = Boolean("s");//返回true，非空字符串
var b3 = Boolean(0);//返回false，数字0
var b4 = Boolean(1);//返回true，非0数字
var b5 = Boolean(-1);//返回true，非0数字
var b6 = Boolean(null);//返回false
var b7 = Boolean(undefined);//返回false
var b8 = Boolean(new Object());//返回true，对象

Number(false) //返回0
Number(true) //返回1
Number(undefined) //返回NaN
Number(null) //返回0
Number("1.2") //返回1.2
Number("12") //返回12
Number("1.2.3") //返回NaN
Number(new Object()) //返回NaN
Number(123) //返回123

var s1 = null;
var s2 = String(t1);//s2的值是 "null"
var s3 = s1.toString();//会报错
var s4;
var s5 = String(t4);//s5的值是 "undefined"
var s6 = t4.toString();//会报错