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Allowing valid characters

To use this method, insert it into the HTML code for a text box (either

) along

with the

invalidchars

attribute:

<input type=”text” invalidchars=”0123456789”

onkeypress=”return TextUtil.blockChars(this, event) “ />

<textarea rows=”10” cols=”25” invalidchars=”0123456789”

onkeypress=”return TextUtil.blockChars(this, event)” />

This one function can be used to block characters in a variety of useful ways:

<input type=”text” onkeypress=”return FormUtil.block(this, event)”

invalidchars=”0123456789” />

<input type=”text” onkeypress=”return FormUtil.block(this, event) “

invalidchars=”ABCDEFGHIJKLMNOPQRSTUVWXYZ” />

<input type=”text” onkeypress=”return FormUtil.block(this, event)”

invalidchars=”abcdefghijklmnopqrstuvwxyz” />

<input type=”text” onkeypress=”return FormUtil.block(this, event)”

invalidchars=” “ />

Allowing valid characters

Naturally, the other method of restricting user input is to only allow certain characters in a text box.

Once again, the easiest way to accomplish this is to add an HTML attribute to a text box:

This example would allow the numbers 0 through 9 only, and no other characters. Naturally, you’ll need

to have an

allowChars()

method that does the opposite of the

blockChars()

method:

TextUtil.allowChars = function (oTextbox, oEvent) {

oEvent = EventUtil.formatEvent(oEvent);

var sValidChars = oTextbox.getAttribute(“validchars”);

var sChar = String.fromCharCode(oEvent.charCode);

var bIsValidChar = sValidChars.indexOf(sChar) > -1;

return bIsValidChar || oEvent.ctrlKey;

};

As you can see, the

allowChars()

has a lot in common with

blockChars()

: It accepts the text box and

the event object as arguments; it formats the event object using

EventUtil.formatEvent()

; it stores

the character that will be entered into the text box in a variable using

String.fromCharCode()

. The

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