72d545a3aacf73830ad019134a025794ed01ce1eDav Glass<p>`Lang` contains JavaScript language utilities and extensions that are used in the YUI library.

72d545a3aacf73830ad019134a025794ed01ce1eDav Glass

72d545a3aacf73830ad019134a025794ed01ce1eDav Glass

72d545a3aacf73830ad019134a025794ed01ce1eDav Glass```

72d545a3aacf73830ad019134a025794ed01ce1eDav Glassvar Y = YUI();

72d545a3aacf73830ad019134a025794ed01ce1eDav Glass

72d545a3aacf73830ad019134a025794ed01ce1eDav Glass// true, an array literal is an array

72d545a3aacf73830ad019134a025794ed01ce1eDav GlassY.Lang.isArray([1, 2]);

72d545a3aacf73830ad019134a025794ed01ce1eDav Glass

72d545a3aacf73830ad019134a025794ed01ce1eDav Glass// false, an object literal is not an array

72d545a3aacf73830ad019134a025794ed01ce1eDav GlassY.Lang.isArray({"one": "two"});

72d545a3aacf73830ad019134a025794ed01ce1eDav Glass

72d545a3aacf73830ad019134a025794ed01ce1eDav Glass// however, when declared as an array, it is true

72d545a3aacf73830ad019134a025794ed01ce1eDav Glassfunction() {

72d545a3aacf73830ad019134a025794ed01ce1eDav Glass var a = new Array();

72d545a3aacf73830ad019134a025794ed01ce1eDav Glass a["one"] = "two";

72d545a3aacf73830ad019134a025794ed01ce1eDav Glass return Y.Lang.isArray(a);

72d545a3aacf73830ad019134a025794ed01ce1eDav Glass}();

72d545a3aacf73830ad019134a025794ed01ce1eDav Glass

72d545a3aacf73830ad019134a025794ed01ce1eDav Glass// false, a collection of elements is like an array, but isn't

72d545a3aacf73830ad019134a025794ed01ce1eDav GlassY.Lang.isArray(document.getElementsByTagName("body"));

72d545a3aacf73830ad019134a025794ed01ce1eDav Glass

72d545a3aacf73830ad019134a025794ed01ce1eDav Glass// true, false is a boolean

72d545a3aacf73830ad019134a025794ed01ce1eDav GlassY.Lang.isBoolean(false);

72d545a3aacf73830ad019134a025794ed01ce1eDav Glass

72d545a3aacf73830ad019134a025794ed01ce1eDav Glass// false, 1 and the string "true" are not booleans

72d545a3aacf73830ad019134a025794ed01ce1eDav GlassY.Lang.isBoolean(1);

72d545a3aacf73830ad019134a025794ed01ce1eDav GlassY.Lang.isBoolean("true");

72d545a3aacf73830ad019134a025794ed01ce1eDav Glass

72d545a3aacf73830ad019134a025794ed01ce1eDav Glass// null is null, but false, undefined and "" are not

72d545a3aacf73830ad019134a025794ed01ce1eDav GlassY.Lang.isNull(null); // true

72d545a3aacf73830ad019134a025794ed01ce1eDav GlassY.Lang.isNull(undefined); // false

72d545a3aacf73830ad019134a025794ed01ce1eDav GlassY.Lang.isNull(""); // false

72d545a3aacf73830ad019134a025794ed01ce1eDav Glass

72d545a3aacf73830ad019134a025794ed01ce1eDav Glass// a function is a function, but an object is not

72d545a3aacf73830ad019134a025794ed01ce1eDav GlassY.Lang.isFunction(function(){}); // true

72d545a3aacf73830ad019134a025794ed01ce1eDav GlassY.Lang.isFunction({foo: "bar"}); // false

72d545a3aacf73830ad019134a025794ed01ce1eDav Glass

72d545a3aacf73830ad019134a025794ed01ce1eDav Glass// true, ints and floats are numbers

72d545a3aacf73830ad019134a025794ed01ce1eDav GlassY.Lang.isNumber(0);

72d545a3aacf73830ad019134a025794ed01ce1eDav GlassY.Lang.isNumber(123.123);

72d545a3aacf73830ad019134a025794ed01ce1eDav Glass

72d545a3aacf73830ad019134a025794ed01ce1eDav Glass// false, strings that can be cast to numbers aren't really numbers

72d545a3aacf73830ad019134a025794ed01ce1eDav GlassY.Lang.isNumber("123.123");

72d545a3aacf73830ad019134a025794ed01ce1eDav Glass

72d545a3aacf73830ad019134a025794ed01ce1eDav Glass// false, undefined numbers and infinity are not numbers we want to use

72d545a3aacf73830ad019134a025794ed01ce1eDav GlassY.Lang.isNumber(1/0);

72d545a3aacf73830ad019134a025794ed01ce1eDav Glass

72d545a3aacf73830ad019134a025794ed01ce1eDav Glass// true, objects, functions, and arrays are objects

72d545a3aacf73830ad019134a025794ed01ce1eDav GlassY.Lang.isObject({});

72d545a3aacf73830ad019134a025794ed01ce1eDav GlassY.Lang.isObject(function(){});

72d545a3aacf73830ad019134a025794ed01ce1eDav GlassY.Lang.isObject([1,2]);

72d545a3aacf73830ad019134a025794ed01ce1eDav Glass

72d545a3aacf73830ad019134a025794ed01ce1eDav Glass// false, primitives are not objects

72d545a3aacf73830ad019134a025794ed01ce1eDav GlassY.Lang.isObject(1);

72d545a3aacf73830ad019134a025794ed01ce1eDav GlassY.Lang.isObject(true);

72d545a3aacf73830ad019134a025794ed01ce1eDav GlassY.Lang.isObject("{}");

72d545a3aacf73830ad019134a025794ed01ce1eDav Glass

72d545a3aacf73830ad019134a025794ed01ce1eDav Glass// strings

72d545a3aacf73830ad019134a025794ed01ce1eDav GlassY.Lang.isString("{}"); // true

72d545a3aacf73830ad019134a025794ed01ce1eDav GlassY.Lang.isString({foo: "bar"}); // false

72d545a3aacf73830ad019134a025794ed01ce1eDav GlassY.Lang.isString(123); // false

72d545a3aacf73830ad019134a025794ed01ce1eDav GlassY.Lang.isString(true); // false

72d545a3aacf73830ad019134a025794ed01ce1eDav Glass

72d545a3aacf73830ad019134a025794ed01ce1eDav Glass// undefined is undefined, but null and false are not

72d545a3aacf73830ad019134a025794ed01ce1eDav GlassY.Lang.isUndefined(undefined); // true

72d545a3aacf73830ad019134a025794ed01ce1eDav GlassY.Lang.isUndefined(false); // false

72d545a3aacf73830ad019134a025794ed01ce1eDav GlassY.Lang.isUndefined(null); // false

72d545a3aacf73830ad019134a025794ed01ce1eDav Glass```

72d545a3aacf73830ad019134a025794ed01ce1eDav Glass

72d545a3aacf73830ad019134a025794ed01ce1eDav Glass