To check if a variable is an array, use “instanceof. The following is the syntax −
variable instanceof Array
Example
Let’s seen an example to check if the variable “sports” is an array or not?
<xmp>
<html>
<body>
<script>
var sports = [ "tennis", "football", "cricket" ];
if (sports instanceof Array) {
alert('Array!');
} else {
alert('Not an array');
}
</script>
</body>
</html>
</xmp>