Untitled

<script>
var personX = 18;
var personY = 13;

function processArrowKeys(E) {
    if (E.keyCode == 37 || E.keyCode == 38 || E.keyCode == 39 || E.keyCode==40) {
        E.preventDefault();
    }

    if (E.keyCode == 37) {
        if (currentterrain[personX - 1][personY] == 0 || currentterrain[personX - 1][personY] == 1 || currentterrain[personX - 1][personY] == 3) {
            personX--;
        }
    }
    if (E.keyCode == 39) {
        if (currentterrain[personX + 1][personY] == 0 || currentterrain[personX + 1][personY] == 1 || currentterrain[personX + 1][personY] == 3) {
            personX++;
        }
    }
    if (E.keyCode == 38) {
        for (i = 0; i < 3; i++) {
            if (currentterrain[personX][personY - 1] == 0 || currentterrain[personX][personY - 1] == 1 || currentterrain[personX][personY - 1] == 3) {
                personY--;
            }
        }
    }
}
</script>

<body onkeydown="processArrowKeys(event)">

if(E.keyCode==37||E.keyCode==38||E.keyCode==39||E.keyCode==40){if(navigator.appName!="Microsoft Internet Explorer"){E.preventDefault();}}

onload = function() {
    var body = document.body,
    personX = 18,
    personY = 13;

    body.onkeydown = function( E ) {
    E = E || window.event;

    if (E.keyCode == 37 || E.keyCode == 38 || E.keyCode == 39 || E.keyCode==40) {
        if ( E.preventDefault ) {
    	E.preventDefault();
        } else {
    	E.returnValue = false;
        }
    }

    if (E.keyCode == 37) {
        if (currentterrain[personX - 1][personY] == 0 || currentterrain[personX - 1][personY] == 1 || currentterrain[personX - 1][personY] == 3) {
    	personX--;
        }
    }
    if (E.keyCode == 39) {
        if (currentterrain[personX + 1][personY] == 0 || currentterrain[personX + 1][personY] == 1 || currentterrain[personX + 1][personY] == 3) {
    	personX++;
        }
    }
    if (E.keyCode == 38) {
        for (i = 0; i < 3; i++) {
    	if (currentterrain[personX][personY - 1] == 0 || currentterrain[personX][personY - 1] == 1 || currentterrain[personX][personY - 1] == 3) {
    	    personY--;
    	}
        }
    }

    }
}

<body onkeydown="handleArrowKeys(event)">

<body onkeydown="processArrowKeys(event)">

/* ... */
function processArrowKeys(E) {
    if (!E) E = window.event;
/* ... */