Question

I have a form in which I want to disable the submit button if there are any characters other than A-Z, a-z, and 0-9.

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What I have now is…

    <form name=form action=process.cgi method=POST />
    <input type=text name=field1 />
    <input type=password name=field2 />
    <input type=submit value=submit />
    </form>

I am trying to make it so that the details are not submitted untill field1 and field2 only have A-Z, a-z, and 0-9

Answer 1

<input type="text" id="name">
<input type="button" id="but" onClick="validate()" Value="Submit">

And your js

String.prototype.isValid = function(){return /^\w*$/.test(this);}

    function validate() {
    if(document.getElementById('name').value.isValid()){
        alert('valid')   ;             

    } else{
        alert('Invalid')   ;     
    }    
        }

check this demo

Updated to include form submission Updated demo

2nd Update here