Detect time lapse between two key press in Javascript - Stack Overflow

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I am learning javascript and at the same time trying to create a simple script that allows you to type a foreign language on a web browser with your keyboard.

So, when you type a for example, there is a single letter mapped to a, so a single character Դ would appear, however to make a character like 厄 appear, you have to type twice, since this language has more characters than the English alphabet.

So, the problem is with that last character. Normally, I should have to type g and h consecutively in the span of one second to produce the 厄 letter, but I have problems waiting to check if within two characters have been typed within one second of eachother inorder to show that letter.

So, I don't think time interval functions are the way to go about this, but I can't see any other method also.

I am learning javascript and at the same time trying to create a simple script that allows you to type a foreign language on a web browser with your keyboard.

So, when you type a for example, there is a single letter mapped to a, so a single character Դ would appear, however to make a character like 厄 appear, you have to type twice, since this language has more characters than the English alphabet.

So, the problem is with that last character. Normally, I should have to type g and h consecutively in the span of one second to produce the 厄 letter, but I have problems waiting to check if within two characters have been typed within one second of eachother inorder to show that letter.

So, I don't think time interval functions are the way to go about this, but I can't see any other method also.

• javascript

Share Improve this question Follow edited Feb 28, 2017 at 14:29 ʎɹnɔɹǝW asked Feb 28, 2017 at 14:25 ʎɹnɔɹǝWʎɹnɔɹǝW 89122 gold badges88 silver badges1515 bronze badges 8

• 2 Store the last pressed time and measure the difference between it and now for every subsequent key pressed. – alex Commented Feb 28, 2017 at 14:27
• Have them hold down another key such as CTRL when two characters need to be typed consecutively – Dexygen Commented Feb 28, 2017 at 14:29
• @alex I think that's a good idea, I don't know if I can divide the timing a get the response I need. It could e up as a float and would be hard to know which is a two-key-press letter or not – ʎɹnɔɹǝW Commented Feb 28, 2017 at 14:31
• @GeorgeJempty Yeah, that would work if there were few of those two-key-press letter, unfortunatelly, they are like ~50 so it would be cumbersome to use it – ʎɹnɔɹǝW Commented Feb 28, 2017 at 14:33
• 1 Yes but measuring the time between key-presses is guesswork. Better cumbersome and precise in my opinion – Dexygen Commented Feb 28, 2017 at 14:35

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4 Answers 4

Sorted by: Reset to default 3

cautions: check key whether up in keydown() & notify keydown the key is upped in keypress();

   var start = null;
    $('#in').keydown(function (e) {
        if (!start) {//checking is a new user input
            start = $.now();
        }
    }).keyup(function (e) {
        var timeElapsed = $.now() - start;
        start = null;//start the next  timing tracking
         
         console.log(['time elapsed:', timeElapsed, 'ms'].join(' '));
    });

<script src="https://ajax.googleapis./ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<label>
<h2>please input some letter to test</h2>
<input id="in"/>
</label>

another answer about your question,perhaps this is your truly answer.

 function duration(timestamps) {
        var last = timestamps.pop();
        var durations = [];
        while (timestamps.length) {
            durations.push(last - (last = timestamps.pop()));
        }
        return durations.reverse();
    }

    function display(mills) {
        if (mills > 1000)
            return (mills / 1000) + ' s';
        return mills + ' ms';
    }

    var durations = [];

    $('#in').keydown(function (e) {
        durations.push($.now());
    }).keyup(function (e) {
        var current = durations;
        current.push($.now());
        durations = [];
        var timeElapsed = current[current.length - 1] - current[0];

        console.log([
            ['time elapsed:', display(timeElapsed)].join(' '),
            ['keys duration:', duration(current).map(display)].join(' ')
        ].join(' --- '));
    });

<script src="https://ajax.googleapis./ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<label>
    <h2>Please input something to test!</h2>
    <input id="in"/>
</label>

Below is the sample code to measure the elapsed time between any 2 events. I added setTimeout just to give you an example.

var startTime = Date.now();

setTimeout(function(){
	var elapsedTime = Date.now() - startTime;
	console.log('elapsedTime ='+elapsedTime);
}, 100);

Like Alex mentioned, for every press, simply store new Date().getTime(); in a variable, which will get you the latest UTC time. UTC time is given in milliseconds, so on the next key-press, just see if the current time and the stored time differ by 1000!

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