检查输入是否为空JQuery

Question

Hello , There are simple problem in my code, I've put myself as a user, let's assume that if the user click on the space button (in keyboard), So What is the solution.

Here my simple code:

 var name = $('input#name').val(); // get the value of the input field if(name == "" || name == " ") { $('#err-name').fadeIn('slow'); // show the error message error = true; // change the error state to true } 

 <script src="https://ajax.googleapis.com/ajax/libs/jquery/1.11.1/jquery.min.js"></script> 

Answer 1

Use the $.trim function to remove spaces

var name = $.trim( $('input#name').val() ); // get the value of the input field
if(name == "") {
    $('#err-name').fadeIn('slow'); // show the error message
    error = true; // change the error state to true
}

Answer 2

The .trim function in JavaScript removes leading and trailing spaces/new lines. So, if the user just spams space bar, the name.trim() will remove all leading/trailing spaces, resulting in "" and that equals "". Thus, your error code would show.

var name = $('input#name').val(); // get the value of the input field
if(name.trim() == "") {
    $('#err-name').fadeIn('slow'); // show the error message
    error = true; // change the error state to true
}