防止机器人提交表单的JavaScript代码

Question

I need a javascript code to prevents bots from submitting forms. But i need a client side code in javascript that work like CAPTCHA but don't call the server

thank you

Answer 1

Most straight forward and simple way will be to add or edit form data on the fly when the button is actually clicked:

<input type="hidden" name="SubmittedByHuman" value="NO" />
<input type="submit" value="Submit me" onclick="this.form.elements['SubmittedByHuman'] = 'YES';" />

Having this, on the server side check the value of form element called "SubmittedByHuman" - if it will be "NO" it means something bypassed the submit button - or as people mentioned correctly in comments, user did click but has disabled JavaScript.

Answer 2

do something like

<h1>Type the result in the input box : 1+1</h1>

<input id="sum" type="text"/>

and before submitting you check if the value in the input is 2 and then submit it.

To improve this type of code you could randomly create these 2 values in the h1 and save them into a var and before submiting check if input and sum are the same.

Answer 3

I doubt this is possible, as bots are sophisticated enough to bypass most things.

Remember, the bot isn't going to open the webpage in a browser and press submit. It'll probably scan the page for a <form> , make a list of all the <input> fields, and perform a POST request containing all the data for each one.

It won't run any javascript, or press any buttons. You'll have to make the check server-side.