We can use JavaScript to replace a character in a string by using the JavaScript String replace() method.

text.replace(/i/g, 'e');

Let’s say we have the following HTML:

We will update the text: text_with_underscores

If we want to change the underscore characters in the span “text_with_underscores” and replace them with spaces, we will use the replace method in the following JavaScript code:

var text = document.getElementById("span1").textContent.replace(/_/g, ' ');
document.getElementById("span1").innerHTML = text;

This would result in the following:

We will update the text: text with underscores

Using JavaScript to Replace a Character in a String with a Click

In this example, we will let the user input any text they want, and then replace any spaces in the text with underscores(_). We will then display the new text below. If there are no spaces in the text provided, no change will occur.

Here is the HTML setup.

Add text below with spaces.

Below is the JavaScript code which will take the user input using an onclick event and run the function below. The function will get the text using the getElementById method and textContent property, and use the replace() method on the text. We will then update the #results div using the textContent property.

Here is the JavaScript code:

function changeText() {
  var userText = document.getElementById("userVal").value;
  var replacedText = userText.replace(/ /g, '_');
  document.getElementById("results").textContent = replacedText;

The final code and output for this example of how to replace characters in a string using JavaScript is below:

Code Output:

Add text below with spaces.

Full Code:

Add text below with spaces.

Hopefully this article has been useful for you to understand how to use JavaScript to replace a character in string.

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Last Update: February 26, 2024