JS强制类型转换

使用强制类型转换（type casting）处理转换值的类型。使用强制类型转换可以访问特定的值，即使它是另一种类型的。

ECMAScript中可用的3种强制类型转换如下：Boolean(value)——把给定的值转换成Boolean型；Number(value)——把给定的值转换成数字（可以是整数或浮点数）；String(value)——把给定的值转换成字符串。

console.log(Boolean("")); console.log(Boolean("hi")); console.log(Boolean(100)); console.log(Boolean(null)); console.log(Boolean(0)); console.log(Boolean(new Object()));

console.log(Number(false)); console.log(Number(true) ); console.log(Number(undefined) ); console.log(Number(null) ); console.log(Number( "5.5 ") ); console.log(Number( "56 ") ); console.log(Number( "5.6.7 ") ); console.log(Number(new Object()) ); console.log(Number(100) );

var s1 = String(null); //"null"var oNull = null;var s2 = oNull.toString(); //won't work, causes an error 3. 利用js变量弱类型转换