<div id='div1' class="c1"> <span>First Div</span> </div>
<div id='div2' class="c2"> <span>Second Div</span> </div>
<button id='action'>Click to Perform Action</button>
JQuery code to find all span inside the div tag and set new text will be -
$('div').find('span').text('New text');
or
$('div').children('span').text('New text');
If we want to change only in a specific div the mention div id or class like this
$('#div1').find('span').text('New text');// using id
$('.c1').find('span').text('New text'); // using class
Complete example -
<!DOCTYPE html>
<html>
<head>
<script src="https://ajax.googleapis.com/ajax/libs/jquery/3.3.1/jquery.min.js"></script>
</head>
<body>
<h3>
Click to change
</h3>
<div id='div1' class="c1"> <span>First Div span text</span> </div>
<div id='div2' class="c2"> <span>Second Div span text</span> </div>
<button id='action'>Click to Perform Action</button>
<script>
$('#action').click(function() {
$('div').find('span').text('New text'); // change all div
// $('#div1').find('span').text('New text'); //only change div1 using id
// $('.c2').find('span').text('New text');only change div2 using class
// or
// $('div').children('span').text('New text');
});
</script>
</body>
</html>
