扩展javascript键按下的功能

Question

I've a such a small javascript on my website, to control the site by pressing the arrow keys on my keyboard.

document.onkeydown = function(evt) {
    evt = evt || window.event;
    switch (evt.keyCode) {
        case 37:
            leftArrowPressed();
            break;
        case 39:
            rightArrowPressed();
            break;
    }
};

function rightArrowPressed() {
     window.open("next-page.php","_self")
}
function leftArrowPressed() {
     window.open("pre-page.php","_self")
}

If I'm pressing the right-arrow-key the javascript redirects me to the "next-page.php". If I'm pressing the left-arrow-key the javascript redirects me to the "pre-page.php".

I want to extend the script with pressing the + and - key or the q and w key. The current script should not change ideally.

Answer 1

The keyCode for what you want to do are the following :

+ : 107

- : 109

q : 81

w : 88

So using your code, here is what we could do :

document.onkeydown = function(evt) {
        evt = evt || window.event;
        switch (evt.keyCode) {
            case 37:
                //code here
                break;
            case 88:
                //code here
                break;
            case 109:
                leftArrowPressed();
                break;
            case 39:
                //code here
                break;
            case 81:
                //code here
                break;
            case 107:
                rightArrowPressed();
                break;
        }
    };

Answer 2

Inside of document.onkeydown after you've defined evt , log the keyCode values:

console.log(evt.keyCode);

From there you can modify your switch statement as necessary.

Answer 3

You can check this:

switch (evt.keyCode) {
        case 37:
            leftArrowPressed();
            break;
        case 39:
            rightArrowPressed();
            break;
case 107: // for +
            your script
            break;
case 109: // for -
             your script
            break;
case 81: // for q
            your script
            break;
case 87: // for w
            your script
            break;
    }