I have a textbox, and it needs not allow the user to enter any special characters. He can enter:
One more condition is the first letter should be alphabetic.
How can I do a JavaScript verification on each keypress?
add a onKeyUp=javascript:checkChar(this); to the input box.
function checkChar(tBox) {
var curVal = tBox.value;
if ( /[^A-Za-z0-9 ]/.test(curVal) ) {
//do something because he fails input test.
}
}
alernatively to check JUST the key that was pressed you can grab the keycode from the event like so:
onKeyUp=javascript:checkChar(event);
function checkChar(e) {
var key;
if (e.keyCode) key = e.keyCode;
else if (e.which) key = e.which;
if (/[^A-Za-z0-9 ]/.test(String.fromCharCode(key))) {
//fails test
}
}
missed the part about first char, but you can do a test on the textbox value as in the first example:
/^[A-Za-z]/.test(curVal)
or even use the second method but pass the text box as well so you can get it's full value.
