underscore.js _.isWeakMap()用法及代碼示例

Underscore.js是javascript中的一個庫，使對數組，字符串，對象的操作變得更加輕鬆便捷。 _.isWeakMap()函數用於檢查給定對象是否為javascriptweakmap。鏈接underscore.js CDN時“_”作為全局變量附加到瀏覽器。

用法:

_.isWeakMap(object);

Parameters:

object:它是任何javascript對象，例如數組，字符串，映射，集合等。

返回值：它返回布爾值。如果對象是JavaScript的弱映射，則該函數返回true，否則返回false。

為了更好地理解該函數，下麵給出一些示例。

範例1：給定數組時，輸出為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>

輸出：

範例2：

當給出一個弱集時，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>

輸出：

相關用法

注：本文由純淨天空篩選整理自tarun007大神的英文原創作品 Underscore.js _.isWeakMap() Function。非經特殊聲明，原始代碼版權歸原作者所有，本譯文未經允許或授權，請勿轉載或複製。