JavaScript How to Ask User for Input (A Complete Guide)

By

To ask for user input in JavaScript, use the built-in window.prompt() method.

For example:

window.prompt("Enter your name");

This shows the following modal at the top of your page:

JavaScript prompt

Prompt Box in JavaScript

To ask for user input in JavaScript, you can use the built-in prompt box. To show a prompt, use the prompt() method.

This method takes two arguments:

  1. Message. The message that asks the user for input.
  2. Default input. The default input value before the user types anything. This is an optional argument.

The prompt() method returns the user input as a string. If no input is specified, it returns a null.

Here is an example of a prompt in JavaScript:

prompt("Enter your name:", "Alice");

When you run this piece of code, you get a prompt that looks like this:

JavaScript prompt

How to Store User Input in JavaScript

If you ask for user input, you may also want to store it somewhere. To store the input, just assign it to a new variable.

For example:

var nickname = prompt("Enter a name you want to be called");

Now, when a user enters their name and clicks “OK” in the modal, their name will be stored in a variable called nickname.

For instance, let’s create a simple page that asks a user for a name and displays a greeting on the front page. Let’s create a file called index.html on the desktop and add the following HTML/JavaScript there:

<html>  
  <head>   
  </head>  

  <body>  
    <h1 id="welcome"> Hello! </h1>  
  </body>
  
  <script type = "text/javascript">
    var nickname = prompt("Please enter your name: ");

    if (nickname != null) {
      document.getElementById("welcome").innerText =
      "Hello, " + nickname + "!";
    }
  </script> 
</html>

When you open up the index.html page, you are going to see a prompt at first:

javascript prompt that asks user a name

When you enter a name into it, you are going to see the name appear on the front page:

Hello HTML page

And there you have it!

Conclusion

Today you learned how to ask for user input in JavaScript.

To recap, you can ask for user input with the built-in prompt() method. This opens up a prompt box where a user can enter text input. To store this input, assign the prompt to a variable.

Thanks for reading.