Using keycodes for '+' and '-'

Question

Hi I have the following code in my Cesium project and would like to know how I can use other keys other than the characters. Here is what I have at the minute:

function getFlagForKeyCode(keyCode) {
switch (keyCode) {
case 'W'.charCodeAt(0):
    return 'moveForward';
case 'S'.charCodeAt(0):
    return 'moveBackward';
case 'Q'.charCodeAt(0):
    return 'moveUp';
case 'E'.charCodeAt(0):
    return 'moveDown';
case 'D'.charCodeAt(0):
    return 'moveRight';
case 'A'.charCodeAt(0):
    return 'moveLeft';
default:
    return undefined;
}

}

I want to be able to use the - and + keys. How can I achieve this?

Answer 1

Up, down, left and right use the arrow keys which are codes 37-40 and the + and - keys are 187 and 189:

function getFlagForKeyCode(keyCode) {
switch (keyCode) {
case 187:
    return 'moveForward';
case 189:
    return 'moveBackward';
case 38:
    return 'moveUp';
case 40:
    return 'moveDown';
case 39:
    return 'moveRight';
case 37:
    return 'moveLeft';
default:
    return undefined;
}

}

Answer 2

If your keyCode comes from keyup/keydown event, you need to do something like this:

document.addEventListener("keydown", function(e){
    if ((e.shiftKey && e.keyCode == 187) || e.keyCode == 107) {
        e.keyCode = 43; // 43 - char code for "+"
    }

    if (e.keyCode == 189 || e.keyCode == 109) {
        e.keyCode = 45; // 45 - char code for "-"
    }

    getFlagForKeyCode(e.keyCode);

}, false);

And extend your getFlagForKeyCode function

function getFlagForKeyCode (keyCode) {
    switch (keyCode) {
    case 'W'.charCodeAt(0):
        return 'moveForward';
    case 'S'.charCodeAt(0):
        return 'moveBackward';
    case 'Q'.charCodeAt(0):
        return 'moveUp';
    case 'E'.charCodeAt(0):
        return 'moveDown';
    case 'D'.charCodeAt(0):
        return 'moveRight';
    case 'A'.charCodeAt(0):
        return 'moveLeft';
    case '+'.charCodeAt(0):
        // return what you need
    case '-'.charCodeAt(0):
        // return what you need
    default:
        return undefined;
    }
}