<!DOCTYPE html>
<html>
<head>
<style>
#myDIV {
width: 220px;
height: 300px;
border: 1px solid black;
display: -webkit-flex; /* Safari */
display: flex;
}
</style>
</head>
<body>
<p>Click the "Try it" button to set the flex property of ALL DIV elements inside the "myDIV" element:</p>
<button onclick="myFunction()">Try it</button>
<div id="myDIV">
<div style="background-color:coral;">RED</div>
<div style="background-color:lightblue;">BLUE</div>
<div style="background-color:lightgreen;">Green div with more content.</div>
</div>
<p><b>Note:</b> Internet Explorer 9 and earlier versions and do not support the flex property.</p>
<p><b>Note:</b> Internet Explorer 10 supports an alternative, the msFlex property. IE11 and newer versions fully support the flex property (do not need the ms prefix).</p>
<p><b>Note:</b> Safari 6.1 (and newer) supports an alternative, the WebkitFlex property.</p>
<script>
function myFunction() {
var x = document.getElementById("myDIV");
var y = x.getElementsByTagName("DIV");
var i = 0;
for (i; i < y.length; i++) {
y[i].style.msFlex = "1"; // IE10
y[i].style.WebkitFlex = "1"; // Safari 6.1+
y[i].style.flex = "1";
}
}
</script>
</body>
</html>