JavaScript new.target 元属性

new.target伪属性让我们检测函数或构造函数是否在 new运算符的帮助下被调用。

句法：

new.target

下面的示例演示了元属性。

示例 1：在此示例中，调用函数时不使用 new运算符。

HTML

  

    
        GeeksForGeeks
    
  
    
        JavaScript | new.target metaKey property
    
      
    
        click here
    
      
    
  
    
        var el_down = document
                .getElementById("GFG_DOWN");
  
        function Fun() {
            if (!new.target) {
                throw 
    'Fun() is called without new operator';
            }
        }
        function Geeks(event) {
            try {
                Fun();
            } catch (e) {
                el_down.innerHTML = e;
            }
        } 
    

  

输出：

示例 2：在此示例中，使用 new运算符调用函数。

HTML

  

    
        GeeksForGeeks
    
    
        JavaScript | new.target metaKey property
    
  
    
        click here
    
      
    
  
    
        var el_down = document
                .getElementById("GFG_DOWN");
        class Person {
            constructor(name) {
                this.name = name;
                if (!new.target) {
throw 'Function is called without new operator';
                }
                else {
throw 'Function is called with new operator';
                }
            }
        }
        function Geeks(event) {
            try {
                var p = new Person('GFG');
            } catch (e) {
                el_down.innerHTML = e;
            }
        } 
    

  

输出：