(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?

(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?

• javascript

• That depends on the IDE. It works jsfiddle/L364hf7v – Rayon Commented Jan 11, 2016 at 19:19
• What IDE are you using? – MrOnlineCoder Commented Jan 11, 2016 at 19:22
• prompt is a window property function. If window is not in the context of a browser, as @adeneo said, prompt cannot exist. – Sterling Archer Commented Jan 11, 2016 at 19:24
• @SterlingArcher My IDE is webstorm, and I also used window, and it still didn't work. – Alec_N Commented Jan 11, 2016 at 19:41
• if you write window.prompt(), it should be recognized. – ssc-hrep3 Commented Jan 11, 2016 at 19:56

2 Answers 2

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 :)

Open your terminal or mand prompt.

To clear the screen, type the mand clear and press Enter.

Initialize a new npm project by running the mand npm init -y in your terminal or mand prompt. This will create a package.json file with default values.

Install the prompt-sync package by running the mand npm install prompt-sync in your terminal or mand prompt. This package allows synchronous user input.

At the top of your code file, add the following line to import the prompt-sync module and create a prompt object:

const prompt = require("prompt-sync")({ sigint: true });

Save your code file.

Run your code and check if the prompt functionality is working correctly.