Detecting multiple key press in javascript

Question

I'm attempting to detect a number of key combinations in javascript. I need to detect Ctrl + Left, Ctrl + Right, Right, and Left.

So far I'm just trying to detect when Ctrl is pressed. Here's what I have (JSFiddle link):

var keys = {};

$(document).keydown(function (e) {
    keys[e.which] = true;

    printKeys();
});

$(document).keyup(function (e) {
    delete keys[e.which];

    printKeys();
});

function printKeys() {
    var html = '';
    for (var i in keys) {
        html += '<p>i: ' + i + '</p>'
        if (!keys.hasOwnProperty(i)) continue;
        if ($.inArray(17, keys) > -1) 
            html += '<p>ctrl was pressed, return val: ' + $.inArray(17, keys) + '</p>'
    }
    $('#out').html(html);
}

I guess I don't really understand how JQuery's inArray is supposed to work because when I press any key, it just returns -1. The if statement also evaluates to true while I only want it to do that when Ctrl is pressed. How can I fix this so that my if statement properly detects Ctrl being pressed? I'll be able to figure the rest out once I get that working properly.

EDIT: Changed if-statement to evaluate inArray returning > -1

Answer 1

In javascript you would need to capture the value of the window.event.ctrlKey to detect if the control key is being pressed. Here is an example of a function that would use to block pasting from the clipboard into a field using the ctrl+v keyboard shortcut:

    function BlockControlV() {
        var keyPressed = window.event.keyCode;
        var ctrlPressed = window.event.ctrlKey;
        if (ctrlPressed && keyPressed == 86) {

            var ClipBoardData = window.clipboardData.getData('Text')
            ClipBoardData = trim(ClipBoardData)

            if (ClipBoardData != '') {
                if (isNaN(ClipBoardData) == true) {
                    window.event.keyCode = 0;
                }
            }
            else {
                window.event.keyCode = 0;
            }
        }
    } 

Though not exactly relevant to what you're trying to do, you should be able to figure out what direction you should be heading.