The TextBox control offers a MaxLength property, which allows the insertable text into that TextBox be clientside limited to the specified amount of chars.
My questions:
- Is this property only client-side and therefore browser-pedendent?
- Can I rely on the fact, that the Text property contains no text longer than MaxLength is set (only for the DisplayModes named in the MSDN article) or do I manually have to perform a TextBox.Text.SubString(0, DesiredMaxLength) ?
- How does all this behave with disabled java-script?
It does not depend on javascript but that does not make it safe.
Anyone can still post a request using javascript (XmlHttpRequest for example) or just craft a request to send more data than the max-length specification. It's a good way to stop a normal user from over populating a field but it is something you need to double check on the server anyway.
Can I rely on the fact, that the Text property contains no text longer than MaxLength ?
No. Consider it a user-friendliness feature. You will have(as always) re-check on the server. And maybe also check in JavaScript, depending on what its for.
来源：https://stackoverflow.com/questions/2416242/how-reliable-is-the-maxlength-property-of-the-textbox-control