402N/A<p>`Lang` contains JavaScript language utilities and extensions that are used in the YUI library.

402N/A

402N/A

402N/A```

402N/Avar Y = YUI();

402N/A

402N/A// true, an array literal is an array

402N/AY.Lang.isArray([1, 2]);

402N/A

402N/A// false, an object literal is not an array

402N/AY.Lang.isArray({"one": "two"});

402N/A

402N/A// however, when declared as an array, it is true

402N/Afunction() {

402N/A var a = new Array();

402N/A a["one"] = "two";

402N/A return Y.Lang.isArray(a);

402N/A}();

402N/A

402N/A// false, a collection of elements is like an array, but isn't

814N/AY.Lang.isArray(document.getElementsByTagName("body"));

402N/A

814N/A// true, false is a boolean

814N/AY.Lang.isBoolean(false);

814N/A

814N/A// false, 1 and the string "true" are not booleans

java.lang.NullPointerException