【javascript】JS类型——Boolean

1. Boolean
var a = true;
var b = new Boolean(true);
console.log(a,typeof(a));
console.log(b,typeof(b));
结果显示：
true boolean  func.html:10:2
Boolean { true } object

console.log(Boolean(undefined));//false
console.log(Boolean(null));//false
console.log(Boolean(0));//false
console.log(Boolean(-0));//false
console.log(Boolean(NaN));//false
console.log(Boolean(''));//false
console.log(Boolean(false));//false
Number( )与Boolean( )的转换：
console.log(Number(''));//0
console.log(Number(' '));//0
console.log(Boolean(''));//false
console.log(Boolean(' '));//true
对于对象和数组的转换
console.log(Boolean({}));//true
console.log(Boolean([]));//true
 
console.log(Boolean(new Boolean(false)));//true
console.log(Boolean(false));//false
console.log(Boolean(new Boolean(null)));//true
console.log(Boolean(null));//false

Boolean对象是与布尔值对应的包装类型，继承了Object对象的通用方法toString()、toLocaleString()、valueOf()这三个方法

【toString()】

　　toString()方法返回Boolean的字符串值('true'或'false')

【toLocaleString()】

　　toLocaleString()方法返回Boolean的字符串值('true'或'false')

【valueOf()】

　　valueOf()方法返回Boolean的原始布尔值(true或false)

console.log(true.valueOf());//true
console.log(true.toString());//'true'
console.log(true.toLocaleString());//'true'

console.log((new Boolean(false)).valueOf());//false
console.log((new Boolean(false)).toString());//'false'
console.log((new Boolean(false)).toLocaleString());//'false'