How to convert a pixel value to a number value using JavaScript ?

Last Updated : 11 Oct, 2019

The task is to convert the string value containing ‘px’ to the Integer Value with the help of JavaScript. Here, Few approaches are discussed.
Approach 1:

Use parseInt() method which takes string as first argument and return the Integer value.

Example 1: This example uses approach as discussed above

<!DOCTYPE HTML>
<html>
  
<head>
    <title>
        Convert a pixel value to a number value using JavaScript.
    </title>
</head>
  
<body style="text-align:center;">
    <h1 style="color:green;">  
        GeeksForGeeks 
    </h1>
    <p id="GFG_UP" style="font-size: 19px; font-weight: bold;">
    </p>
    <button onclick="GFG_Fun()">
        click here
    </button>
    <p id="GFG_DOWN" 
       style="color: green;
              font-size: 24px; 
              font-weight: bold;">
    </p>
    <script>
        var el_up = document.getElementById("GFG_UP");
        var el_down = document.getElementById("GFG_DOWN");
        var n = el_up.style.fontSize;
        el_up.innerHTML = 
          "Click on the button to get the number value "+
          "from pixel value.<br>Pixel Value - '" + n + "'";
  
        function GFG_Fun() {
            el_down.innerHTML = "Integer value is " + parseInt(n, 10);
        }
    </script>
</body>
  
</html>

Output:

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

Approach 2:

Use RegExp which replaces the ‘px’ by empty string and then convert the result to Integer using Number().

Example 2: This example uses approach as discussed above.

<!DOCTYPE HTML>
<html>
  
<head>
    <title>
        Convert a pixel value to a number value using JavaScript.
    </title>
</head>
  
<body style="text-align:center;">
    <h1 style="color:green;">  
        GeeksForGeeks 
    </h1>
    <p id="GFG_UP" style="font-size: 19px; font-weight: bold;">
    </p>
    <button onclick="GFG_Fun()">
        click here
    </button>
    <p id="GFG_DOWN" 
       style="color: green; 
              font-size: 24px; 
              font-weight: bold;">
    </p>
    <script>
        var el_up = document.getElementById("GFG_UP");
        var el_down = document.getElementById("GFG_DOWN");
        var n = el_up.style.fontSize;
        el_up.innerHTML = "Click on the button to get the "+
          "number value from pixel value.<br>Pixel Value - '" + n + "'";
  
        function GFG_Fun() {
            el_down.innerHTML = 
              "Integer value is " + Number(n.replace(/px$/, ''));
        }
    </script>
</body>
  
</html>

Output:

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

My Personal Notes

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