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Thread: Limit on Increment/Decrement

  1. #1
    Join Date
    Jan 2011
    Posts
    3

    Limit on Increment/Decrement

    Good day, everyone! I'm fairly new to the world of JavaScript but was just curious if anyone can help me with a question I have. I have a script right now that lets me increment/decrement the number in a field by one with each mouse click depending on which button they press. I'm curious what I can do to keep the value between 0 and 9. Here is the simple script I'm starting out with.

    Code:
    function plusminus(num,boo) {
    var val = document.getElementById("num"+num).value;
    (boo) ? val++ : val--;
    document.getElementById("num"+num).value = val;
    }
    It's working very well, but I just need to work the 0-9 limitation into it somehow. If anyone can help me out, it'd be very appreciated. Thanks!

  2. #2
    Join Date
    Jul 2008
    Location
    urbana, il
    Posts
    2,787
    Code:
    function plusminus(num,boo) {
    var val = document.getElementById("num"+num).value;
    (boo) ? val++ : val--;
    if(val>9){val=0;}
    document.getElementById("num"+num).value = val;
    }

  3. #3
    Join Date
    Aug 2009
    Posts
    593
    This limits the number to be between 0-9

    Code:
    function plusminus(num, boo) {
    	var ele = document.getElementById('num' + num);
    	ele.value = Math.min(Math.max((1 * ele.value) + (boo ? 1 : -1), 0), 9);
    }

  4. #4
    Join Date
    Jan 2011
    Posts
    3
    Nice! I went ahead and added a line to keep it from going negative. Is there a sexier way to do it? Either way, this works and I thank you, rnd_me!

    Code:
    function plusminus(num,boo) {
    var val = document.getElementById("num"+num).value;
    (boo) ? val++ : val--;
    if(val>9){val=0;}
    if(val<0){val=0;}
    document.getElementById("num"+num).value = val;
    }

  5. #5
    Join Date
    Jan 2011
    Posts
    3
    Thanks rnd_me and thraddash! rnd_me, after a slight alteration, yours does exactly what I want. And thraddash, yours does it as is. Thanks to both of you. I always like knowing multiple ways of doing things anyway.

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