Can a synchronous input be done in JavaScript?

Question

I'm interested in the possibility of using JavaScript for an introductory language for students. The missing piece for me is the ability to provide a blocking equivalent to the input() command that is available in other languages.

Using console-only versions of JavaScript, like SpiderMonkey , would be a solution. SpiderMonkey has a readline() command. But I think the students would be more interested in code that ran inside a web browser. It would be nice if students could share with their friends their version of the classic "guess a number between 1 and 10" game.

The JavaScript window.prompt() command would also work, but the fact that it pops up a completely separate window isn't ideal. I'd like an in-document input field that works the same way. Is there such a solution?

Answer 1

prompt() is the only thing that comes to mind as a blocking input method. I don't exactly know why you need to make it blocking, but perhaps you can use the jQuery blocking plugin to achieve the blocking (at least the UI)?

Answer 2

I don't think you will find a great way to do that and I'm not sure you should try. I assume this is a very basic course in programming and you want the students to get the feeling they can accomplish something. In that case I would provide them with html code that contains the input field, button and an onclick handler hooked to a function already.

Students will quickly learn to add input fields and buttons. Just because you and I learned to program in text only environments doesn't mean that todays students should.

Answer 3

You con use an input text and a button. when button is pressed get and process the text and clean the input text for a new usage.

In addition you can consider use http://jsfiddle.net/

Answer 4

In a web browser, you can use prompt . It's very old-fashioned (like alert ) and behaves (almost entirely) synchronously. So:

var str;
str = prompt("Enter some text: ", "");
console.log("You entered '" + str + "'");
str = prompt("Enter some more text: ", "");
console.log("You entered '" + str + "'");

Live example | Live source

Instead, though, I think I'd probably recommend getting the students used to using callbacks, and providing some utility code (or just using some pre-built thing). The sooner they get used to it, the better, and it's not that complicated. For instance, the asynchronous version of the above could readily be:

asynchronousPrompt("Enter some text: ", "", function(text) {
    console.log("You entered '" + text + "'");
    asynchronousPrompt("Enter some more text: ", "", function(text) {
        console.log("You entered '" + text + "'");
    });
});

Answer 5

JavaScript中的同步执行为使用JavaScript执行同步操作提供了不错的编写和示例代码。

Answer 6

Would NodeJs be a solution for you? It supports a REPL afaik. And it also has a STDIO implementation