number only field

numberonly.js

numericField = function (elementId) {
    var allowed = [0, 8];

    for (var i = 48; i < 58; i++) {
        allowed.push(i);
    }
    
    $("#" + elementId).keypress(function(e){
        if (!(allowed.indexOf(e.which) >= 0)) {
            e.preventDefault();
        }
    });
};