Client-sided scripts are not effective for security .... they prevent innocent bystanders from attacking you, but malevolent people will side-step your scripts. They resemble a locked front door with a wide open window right next to it.

However, client-side scripts are useful for things like verifying user input. While the scripts can irritate users, especially if poorly written, but submitting a form-full of defective data to the server is worse.

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