JavaScript Object Analyzer

Provides information about structure of a JavaScript object.

Installation

Using npm:

$ npm i --save jsobj-analyzer

In a browser:

<script src="dist/jsoa.min.js"></script>

In node.js:

var JSOA = require('jsobj-analyzer');

Also the module exported as AMD module.

Documentation

• Get Tag
• Flat Inspection
• Deep Inspection

Get Tag

string getTag(Mixed any)

The analyzes needs to determine the type of any variable. This function relies on:

1. used or overridden well-known Symbol toStringTag for objects;
2. read-only property Function.name taken from constructor if the variable has been instantiated;
3. finally result of Object.prototype.toString which can process any variable at all.

Actually built-in method Object.prototype.toString may do all work, but getting type for any user-typed variables is more conveniently by using constructor.name by default if it's possible.

Some examples:

Definition of A | getTag(A) --- | --- 10 | Number Math.PI | Number NaN | Number -0 | Number undefined | Undefined null | Null true | Boolean 'Hello' | String { x: 1, y: 0 } | Object [1, 2, 3] | Array new Set | Set Set | Function JSON | JSON class Animal {} new Animal | Animal (x, y) => x + y | Function function* A(i) { while(1) yield i += 1; } | GeneratorFunction async function A() { /* await a promise and return */ } | AsyncFunction

Flat Inspection

object inspFlat(object obj)

The function collects statistics about an object structure. Requires plain or iterable object as first parameter.

For example let's describe next object:

class Person {
    constructor(name) {
        this.name = name;
    }
}
    
let data = {
    x: 10,
    y: NaN,
    e: Math.E,
    arr: [ 'p1', 'p2', 'p3' ],
    obj: {
        0: new Set([ false ]),
        1: new Set([ true ])
    },
    sum: (a, b) => a + b,
    fn: {
        inc: function(i) {
            return i + 1;
        },
        Person,
        man: new Person('John')
    },
    date: new Date
};

console.log(JSOA.inspFlat(data));

The output will be:

{ Number: 3, Array: 1, Object: 2, Function: 1, Date: 1 }

Deep Inspection

object inspFlat(object obj, number maxDepth = 6)

Unlike the previous function collects statistics recursively over all nested plain and iterable objects too.

The same data with deep inspection:

console.log(JSOA.inspDeep(data));

The output will be:

{ Number: 3, String: 3, Boolean: 2, Function: 3, Person: 1, Date: 1 }

The optional second parameter maxDepth limits the depth of inspection. By default is 6: it's enough for most cases.

Changelog

0.1.4

• Supported parameter maxDepth for deep inspection (Closed Issue #2)