javascript "prompt is not defined" Reference Error

Question

(function() {
    var random_num = Math.floor(Math.random()*10) + 1;
    var input_num = prompt("Guess the number between 1 and 10");
    if (input_num < 1 || input_num > 10) {
        alert('the input number is not between 1 and 10');

    } else if (random_num == input_num) {
        alert('Good Work');
    } else {
        alert('Not matched, the random number is: ' + random_num);
    }

})();

But the IDE displays that "prompt" is not defined. Could someone help me explain why?

Answer 1

Assuming you're using JSHint in WebStorm, set Preferences > Languages & Frameworks > JavaScript > Code Quality Tools > JSHint > Environments > Browser to true

Screenshot of WebStorm settings

Update: Also, as mentioned earlier, for good code you should use window.prompt, just so it's clear you're using the built in browser prompt rather than a custom function etc... (the same goes for alert, so use window.alert)

Finally, unrelated to the question, but something I noticed - it's good practice to use the === operator. There are a million articles online explaining why :)