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Underscore.js _.isWeakMap()用法及代码示例

Underscore.js是javascript中的一个库,使对数组,字符串,对象的操作变得更加轻松便捷。 _.isWeakMap()函数用于检查给定对象是否为javascriptweakmap。链接underscore.js CDN时“_”作为全局变量附加到浏览器。

用法:

_.isWeakMap(object);

Parameters: 

  • object:它是任何javascript对象,例如数组,字符串,映射,集合等。

返回值:它返回布尔值。如果对象是JavaScript的弱映射,则该函数返回true,否则返回false。

为了更好地理解该功能,下面给出一些示例。



范例1:给定数组时,输出为false。

<!DOCTYPE html> 
<html lang="en"> 
<head> 
  <meta charMap="UTF-8"> 
  <meta name="viewport" 
        content="width=device-width, initial-scale=1.0"> 
  <title>Document</title> 
  <script src= 
"https://cdnjs.cloudflare.com/ajax/libs/underscore.js/1.9.1/underscore-min.js" >  
  </script>  
</head> 
<body> 
  <script> 
    //creating a array of size 2 using constructor 
    var obj= new Array(2); 
    //filling value 10in the array 
    obj.fill(5) 
    //using the underscore.js function _.weakMap() 
    var isWeakMap= _.isWeakMap(obj); 
    console.log(isWeakMap) 
    //If the given object is weakMap it prints the object is weak Map. 
    if(isWeakMap) 
    console.log(`The ${obj} is the WeakMap of Javascript.`) 
    else
    console.log(`The ${obj} is not the WeakMap of Javascript.`) 
  </script> 
</body> 
</html>

输出:

范例2:

当给出一个弱集时,它返回true。

<!DOCTYPE html> 
<html lang="en"> 
<head> 
  <meta charMap="UTF-8"> 
  <meta name="viewport" 
        content="width=device-width, initial-scale=1.0"> 
  <title>Document</title> 
  <script src= 
"https://cdnjs.cloudflare.com/ajax/libs/underscore.js/1.9.1/underscore-min.js" >  
  </script>  
</head> 
<body> 
  <script> 
    //creating a array of size 2 using constructor 
    var obj= new WeakMap(); 
    //using the underscore.js function _.weakMap() 
    var isWeakMap= _.isWeakMap(obj); 
    console.log(isWeakMap) 
    //If the given object is weakMap it prints the object is weak Map. 
    if(isWeakMap) 
    console.log(`The ${obj} is the WeakMap of Javascript.`) 
    else
    console.log(`The ${obj} is not the WeakMap of Javascript.`) 
  </script> 
</body> 
</html>

输出:

相关用法

注:本文由纯净天空筛选整理自tarun007大神的英文原创作品 Underscore.js _.isWeakMap() with Examples。非经特殊声明,原始代码版权归原作者所有,本译文的传播和使用请遵循“署名-相同方式共享 4.0 国际 (CC BY-SA 4.0)”协议。