Canceled JavaScript prompt

Canceled prompt

Question: What value does prompt() return if the user clicked the Cancel button?

Answer: The return value of canceled prompt() depends on the browser. In most browsers the return value is null; however, some very old browsers (e.g. early versions of IE) used to return '' (an empty string).

Therefore, when calling prompt(), you may want to use an if statement like this:

userInput = prompt('Prompt text','Suggested input');
if (userInput != '' && userInput != null) {
 // do something with the input
}

This code can be simplified to:

userInput = prompt('Prompt text','Suggested input');
if (userInput) {
 // do something with the input
}