js的显性转化Boolean()

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js的显性转化Boolean()

该方法将值转化为布尔类值

var a = Boolean(123)
typeof( a )
//a = true,a为Boolean类型 

var a = Boolean("abc")
typeof( a )
// a = true,a为boolean类型

var a = Boolean( 0 )
typeof( a );
//a = false,a为boolean类型

var a = Boolean(" 0 ")
typeof( a )
//a = true，a为boolean类型

var a = Boolean(undefined);
console.log( a );
//控制台打印false, a = false,a为Booolean类型 

var a = Boolean( null )
console.log( a )
//控制台打印false, a = false;a为Booleanl类型

var b = Boolean(document);
console.log( b );
//控制台打印true,b = true

var b = Boolean(Object);
console.log( b );
//控制台打印true,b = true,b为boolean类型

var b = Boolean(window);
console.log( b );
//控制台打印出true，b = true,b为布尔类型

当转化值为null,undefined,数值0时，会将其转化为false