Js Method for Determining Object Types

Read the excerpt from the JavaScript authoritative guide (Rhino) 9.7 to determine the object type. 1. typeof supports obtaining basic types, such as boolean, string, number, function, object, and undefined. Usage: varvtrue; // & quot; string & quot;, typeo...

Read the excerpt from the JavaScript authoritative guide (Rhino) 9.7 to determine the object type.

1. typeof

Basic types are supported, such as boolean, string, number, function, object, and undefined.

Usage:

Var v = true; // "string ",

Typeof v; // boolean

PS: Array, Date, and null are all objects, and undefined is undefined.

2. instanceof

When you determine whether a value is a function or object, you can use instanceof for more details.

Usage:

Var v = new Date ();

V instanceof object; // true

V instanceof Date; // true

3. constructor

Constructor properties are a more step-by-step method than instanceof.

Var v = new Date ();

V. constructor = Object; // true note: the constructor of the type to be detected is on the right of the equal sign.

V. constructor = Date; // true

 

From screepinail