JavaScript,布尔Boolean(布尔)对象用于将非布尔值转换为布尔值(true 或者 false)。
检查布尔值 检查布尔对象是 true 还是 false。 源代码示例: <!DOCTYPE html><html><body><script>var b1=new Boolean(0);var b2=new Boolean(1);var b3=new Boolean("");var b4=new Boolean(null);var b5=new Boolean(NaN);var b6=new Boolean("false");document.write("0 is boolean "+ b1 +"<br>");document.write("1 is boolean "+ b2 +"<br>");document.write("An empty string is boolean "+ b3 + "<br>");document.write("null is boolean "+ b4+ "<br>");document.write("NaN is boolean "+ b5 +"<br>");document.write("The string 'false' is boolean "+ b6 +"<br>");</script></body></html> 测试结果:
0 is boolean false1 is boolean trueAn empty string is boolean falsenull is boolean falseNaN is boolean falseThe string 'false' is boolean true 创建 Boolean 对象 Boolean 对象代表两个值:"true" 或者 "false" 下面的代码定义了一个名为 myBoolean 的布尔对象:
var myBoolean=new Boolean(); 如果布尔对象无初始值或者其值为:
0-0null""falseundefinedNaN 那么对象的值为 false。否则,其值为 true(即使当自变量为字符串 "false" 时)! JavaScript,布尔
|