The default parameter came to handle function parameters with ease. Default parameters allow you to initialize formal parameters with default values. This is possible only if no value or undefined is passed. With ES6, you can easily set default parameters. Let’s see an example
Example
Live Demo
<html>
<body>
<script>
// default is set to 1
function inc(val1, inc = 1) {
return val1 + inc;
}
document.write(inc(10,10));
document.write("<br>");
document.write(inc(10));
</script>
</body>
</html>The following code runs correctly showing the working of parameters from left-to-right. It overwrites default parameters even if parameters are added after without default.
Example
Live Demo
<html>
<body>
<script>
function display(val1 = 10, val2) {
return [val1, val2];
}
document.write(display());
document.write(display(20));
</script>
</body>
</html>