How to wait 2 seconds for input in Javascript

Question

I im programming tv remote control using javascript and need when user press number 1 function waits 2 seconds if user press one more time 1 (1 channel or 11 channel or 111channel).

i write this function but it gets on display only 11111111 in loop here is my code:

 function chChannel(pressed) {
     setInterval(function () {
         if (lengthCS < 3) {
             inputChannel += pressed;
             lengthCS = inputChannel.length;
         }
     }, 2000);

     // call function to change channel using variable value inputChannel for ex. 011
 };

Any solution please?

So function need to wait 2seconds and then after 2seconds it gets value of pressed numbers in variable InputChannel so that i can then call function to change channel to number from Value InputChannel.

Answer 1

Listening to keypresses and counting them is one well documented thing, but, in context with the actual topic, I would say, there is no correct Waiting method, other than to end the script with a timeout call being set to a function that repeatedly checks, whether the Time to wait has passed by, if not then selftrigger with setTimeout in eg. 100ms, if yes then call a function that continues the main program. The Waiting thread may then also check and count keypresses, eg. in global variables as a basic solution.

Answer 2

use "setTimeout".

var Timer;

function chChannel(pressed) {
    clearTimeout(Timer);
    Timer = setTimeout(function () {
        if (lengthCS < 3) {
            inputChannel += pressed;
            lengthCS = inputChannel.length;
        }
    }, 2000);

    // call function to change channel using variable value inputChannel for ex. 011
};

Answer 3

Have you considered using something like underscore's debounce function, would make things a lot simpler all round.

http://underscorejs.org/#debounce

May be something like this might work, on phone can't test it myself...

var inputChannel;

 function chChannel(pressed) {
     if (inputChannel <= 3) {
         inputChannel += pressed;
     } 
     else {
        inputChannel = pressed;
    }
    _.debounce(someFunction, 2000);
 };

As long as debounce keeps getting called within the delay it will not execute, and only execute once after the delay.