Avoid Special Characters on Key press using JavaScript

HTML

<input type="text" onkeypress="avoidSplChars(event)" >

JavaScript function

function avoidSplChars(e) {
    e = e || window.event;
    var bad = /[^\sa-z\d]/i,
        key = String.fromCharCode(e.keyCode || e.which);
    if (e.which !== 0 && e.charCode !== 0 && bad.test(key)) {
        e.returnValue = false;
        if (e.preventDefault) {
            e.preventDefault();
        }
    }
}

Hope this helps!!