What Does the jQuery $.type() Method Determine?

The jQuery $.type() method determines the internal JavaScript data type of a given value and returns it as a lowercase string. Unlike JavaScript's native typeof operator, which categorizes many distinct reference types simply as "object", $.type() provides a more accurate and granular identification by inspecting the internal [[Class]] of the operand. This makes it particularly useful for distinguishing between plain objects, arrays, dates, regular expressions, and null.

How jQuery $.type() Works

The method evaluates the passed value against standard JavaScript types using an internal mapping mechanism combined with Object.prototype.toString.call().

When evaluated, it resolves values to their specific type name:

  • Prims and Special Values:

    • undefined returns "undefined"
    • null returns "null"
    • true or false returns "boolean"
    • Numbers (including NaN and Infinity) return "number"
    • Strings return "string"
    • Symbols return "symbol"

  • Built-in Objects:

    • [] returns "array"
    • {} returns "object"
    • function(){} returns "function"
    • new Date() returns "date"
    • /test/ or new RegExp() returns "regexp"
    • new Error() returns "error"

Difference Between typeof and $.type()

JavaScript's native typeof operator has known quirks that can complicate type checking:

typeof null;        // "object"
typeof [];          // "object"
typeof new Date();  // "object"
typeof /abc/;       // "object"

The $.type() method normalizes these differences to return explicit, predictable types:

$.type(null);        // "null"
$.type([]);          // "array"
$.type(new Date());  // "date"
$.type(/abc/);       // "regexp"

Deprecation Status

In modern web development, jQuery.type() is deprecated as of jQuery 3.3.0 and removed in jQuery 4.0. Modern ECMAScript features provide standardized alternatives without requiring a library, such as Array.isArray(), the standard typeof operator for primitives, and instanceof or Object.prototype.toString.call(val).slice(8, -1).toLowerCase() for advanced object classification.