Javascript that prevents double click on submit button

This is what happening:

• The user loves "double clicking" on any button even though single click will trigger the action.
• The Internet connection slows down and the user thought that he did not click on the correct button. So, he decided to click it again even though the waiting time is lesser than 1 second (?!).

To solve this, you need the following JavaScript to ensure that the submit is working with single click only. Note: you may adjust the value of "500" (ms) to whatever value that you want.

var _prev_save_click_ts = null;

function beforeSubmit() {

    if (_prev_save_click_ts != null) {
        var ts = new Date();

        if (ts - _prev_save_click_ts < 500) {
            // user is double clicking.
            return false;
        }
    }

    _prev_save_click_ts = new Date();
    return true;
}