How to check a selector matches some content using jQuery?

In order to know whether the jQuery selector selected any element or not, Here 2 methods are discussed and these are mostly used methods. Example-1: In this example, Selector searches for <p> element. This example uses the length property to check If something is selected or not. In this case <p> element is found.

html

<!DOCTYPE html>
<html>

<head>
    <title>
        JQuery | 
      check if a selector matches something.
    </title>
    <script src=
"https://ajax.googleapis.com/ajax/libs/jquery/3.4.0/jquery.min.js">
  </script>
</head>

<body style="text-align:center;" id="body">
    <h1 style="color:green;">  
            GeeksForGeeks  
        </h1>
    <p>
        A computer science portal for geeks.
    </p>
    <button onclick="gfg_Run()">
        check
    </button>
    <p id="GFG_DOWN" 
       style="color:green; 
              font-size: 20px;">
    </p>
    <script>
        var el_down = 
            document.getElementById("GFG_DOWN");
        var str = '';

        function gfg_Run() {
            if ($("p").length) {
                str = "Something Selected";
            } else {
                str = "Nothing Selected";
            }
            el_down.innerHTML = str;
        }
    </script>
</body>

</html>

Output:

Before clicking on the button:
After clicking on the button:

Example-2: In this example, Selector searches for <a> element. This example also uses the length property to check, If something is selected or not. In this case <a> element is not found.

html

<!DOCTYPE html>
<html>

<head>
    <title>
        JQuery | 
      check if a selector matches something.
    </title>
    <script src=
"https://ajax.googleapis.com/ajax/libs/jquery/3.4.0/jquery.min.js">
  </script>
</head>

<body style="text-align:center;" id="body">
    <h1 style="color:green;">  
            GeeksForGeeks  
        </h1>
    <p>
        A computer science portal for geeks.
    </p>
    <button onclick="gfg_Run()">
        check
    </button>
    <p id="GFG_DOWN" 
       style="color:green;
              font-size: 20px;">
    </p>
    <script>
        var el_down = 
            document.getElementById("GFG_DOWN");
        var str = '';

        function gfg_Run() {
            if ($("a").length) {
                str = "Something Selected";
            } else {
                str = "Nothing Selected";
            }
            el_down.innerHTML = str;
        }
    </script>
</body>

</html>

Output:

Before clicking on the button:
After clicking on the button:

Example-3: In this example, Selector searches for <button> element. This example uses the exists function to check, If something is selected or not. In this case <button> element is found.

html

<!DOCTYPE html>
<html>

<head>
    <title>
        JQuery | 
      check if a selector matches something.
    </title>
    <script src=
"https://ajax.googleapis.com/ajax/libs/jquery/3.4.0/jquery.min.js">
  </script>
</head>

<body style="text-align:center;" id="body">
    <h1 style="color:green;">  
            GeeksForGeeks  
        </h1>
    <p>
        A computer science portal for geeks.
    </p>
    <button onclick="gfg_Run()">
        check
    </button>
    <p id="GFG_DOWN" 
       style="color:green; 
              font-size: 20px;">
    </p>
    <script>
        var el_down = 
            document.getElementById("GFG_DOWN");
        var str = '';
        jQuery.fn.exists = function() {
            return this.length > 0;
        }

        function gfg_Run() {
            if ($("button").exists()) {
                str = "Something Selected";
            } else {
                str = "Nothing Selected";
            }
            el_down.innerHTML = str;
        }
    </script>
</body>

</html>

Output:

Before clicking on the button:
After clicking on the button:

How to check a selector matches some content using jQuery?

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