JavaScript布尔如何使用valueOf()方法?

2021年3月18日16:20:51 发表评论 587 次浏览

以下是示例布尔值valueOf()方法。

boolean.valueOf()方法用于返回布尔值, 或者true" 要么 "false", 具体取决于指定的布尔对象的值。

语法如下:

boolean.valueOf()

参数:此方法不接受任何参数。

返回值:它根据指定的布尔对象的值返回布尔值" true"或" false"。

上述方法的更多代码如下:

程序1:

<script>
   // Here Boolean object obj is created 
   // for the value true.
   var obj = new Boolean( true );
  
   // Here boolean.valueOf() function is 
   // used for the created object obj.
   document.write(obj.valueOf());
</script>

输出如下:

true

程式2:

<script>
   // Here Boolean object obj is
   // created for the value 1.
   var obj = new Boolean(1);
  
   // Here boolean.valueOf() function 
   // is used for the created object obj.
   document.write(obj.valueOf());
</script>

输出如下:

true

程式3:

<script>
   // Here Boolean object obj is 
   // created for the value -1.
   var obj = new Boolean(-1);
  
   // Here boolean.valueOf() function
   // is used for the created object obj.
   document.write(obj.valueOf());
</script>

输出如下:

true

计划4:

<script>
   // Here Boolean object obj is 
   // created for the value 1.2
   var obj = new Boolean(1.2);
  
   // Here boolean.valueOf() function 
   // is used for the created object obj.
   document.write(obj.valueOf());
</script>

输出如下:

true

计划5:

<script>
   // Here Boolean object obj is 
   // created for the value as string "gfg"
   var obj = new Boolean( "gfg" );
  
   // Here boolean.valueOf() function is 
   // used for the created object obj.
   document.write(obj.valueOf());
</script>

输出如下:

true

计划6:

<script>
   // Here Boolean object obj is created for the value false.
   var obj = new Boolean( false );
  
   // Here boolean.valueOf() function is
   // used for the created object obj.
   document.write(obj.valueOf());
</script>

输出如下:

false

计划7:

<script>
   // Here Boolean object obj is created 
   // for the value zero (0)
   var obj = new Boolean(0);
  
   // Here boolean.valueOf() function is 
   // used for the created object obj.
   document.write(obj.valueOf());
</script>

输出如下:

false

错误和异常:在控制台上检查该程序。

程序1:

这里的值lsbin会给出错误, 因为不仅未定义该值, 而且还预定义了false。

<script>
   // Here Boolean object obj is created 
   // for the value lsbin.
   var obj = new Boolean(lsbin);
  
   // Here boolean.valueOf() function is
   // used for the created object obj.
   console.log(obj.valueOf());
</script>

输出如下:

Error: lsbin is not defined

程式2:

此处不能将复数作为参数, 而只能将整数值和字符串作为参数, 这就是它返回错误的原因。

<script>
   // Here Boolean object obj is created 
   // for the value such as complex number 1+2i
   var obj = new Boolean(1 + 2i);
  
   // Here boolean.valueOf() function is
   // used for the created object obj.
   console.log(obj.valueOf());

输出如下:

Error: Invalid or unexpected token

支持的浏览器:支持的浏览器JavaScript布尔valueOf()方法下面列出:

谷歌浏览器

IE浏览器

火狐浏览器

苹果浏览器

歌剧


木子山

发表评论

:?: :razz: :sad: :evil: :!: :smile: :oops: :grin: :eek: :shock: :???: :cool: :lol: :mad: :twisted: :roll: :wink: :idea: :arrow: :neutral: :cry: :mrgreen: