JSFiddle - React, Tailwind, and code Playground

HTML

<input type="checkbox">
<input type="button" value="Trigger">

<p>
    First, try clicking on the ckeck-box. You'll notice that
    the ckecked property is updated BEFORE the click handler
    is executed.
</p>

<p>
    Then, click on the "Trigger" button. You'll see that 
    the ckecked property is NOT updated before the click
    handler is executed.
</p>

JavaScript

var checkbox = $('input:checkbox'),
    button = $('input:button');

checkbox.click(function() {
    alert( this.checked );    
});

button.click(function() {
   checkbox.click();
});