如何在 JavaScript 中使 Array.indexOf() 不区分大小写？

任务是使Array.indexOf() 方法不区分大小写。以下是一些在 JavaScript 帮助下讨论最多的技术。

• .toLowerCase() 方法
• .toUpperCase() 方法

.toLowerCase() 方法：使用 .toLowerCase() 方法将搜索字符串和数组元素转换为小写，然后执行简单搜索。下面的例子说明了该方法。

示例 1：

  

    
        How to use Array.indexOf() case
        insensitive in JavaScript ?
    

  

      
     
        Geeksforgeeks 
    
      
    
    
      
    
        Click Here
    
      
    
    
    
        var el_up = document.getElementById("GFG_UP");
        var el_down = document.getElementById("GFG_DOWN");
          
        var arr = ['GFG_1', 'geeks',
            'Geeksforgeeks', 'GFG_2', 'gfg'];
          
        var el = 'gfg_1';
          
        el_up.innerHTML = "Click on the button for "
                + "case-insensitive search. <br>Array = '"
                + arr + "'<br>Element = '" + el + "'";
  
        function gfg_Run() {
            res = arr.findIndex(item => 
                el.toLowerCase() === item.toLowerCase());
              
            el_down.innerHTML = "The index of '" + 
                        el + "' is '" + res + "'.";
        }
    

  

输出：

.toUpperCase() 方法：使用 .toUpperCase() 方法将搜索字符串和数组元素转换为大写，然后执行简单搜索。下面的例子说明了这种方法。

示例 2：

  

    
        How to use Array.indexOf() case
        insensitive in JavaScript ?
    

  

     
        GeeksforGeeks 
    
      
    
    
      
    
        Click Here
    
      
    
    
      
    
        var el_up = document.getElementById("GFG_UP");
        var el_down = document.getElementById("GFG_DOWN");
      
        var arr = ['GFG_1', 'geeks',
                'GeeksforGeeks', 'GFG_2', 'gfg'];
          
        var el = 'gfg_1';
          
        el_up.innerHTML = "Click on the button for "
                + "case-insensitive search. <br>Array = '"
                + arr + "'<br>Element = '" + el + "'";
  
        function gfg_Run() {
            var res = arr.find(key => key.toUpperCase() === 
                            el.toUpperCase()) != undefined;
            if (res) {
                res = 'present';
            } else {
                res = 'absent';
            }
            el_down.innerHTML = "The element '" + el
                + "' is '" + res + "' in the array.";
        }
    

  

输出：