returning false not stopping the submission of form

Question

My purpose: If the user field and password field are blank, I want to stop form submitting. This is my Code that I am trying:

Answer 1

Using addEventListener on submit with preventDefault()

document.form1.addEventListener( "submit", function(event) {

    var user = this.querySelector("input[name=user]").value; // this = object of form1
    var pass = this.querySelector("input[name=pass]").value;

    if ( (user.trim() == "") || (pass.trim() == "") ) {
        alert("cannot Submit form");
        event.preventDefault();
    } else {
        alert("submit");
    }

} );

    Username: 


    Password: 

    

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