Pretty-print Object

Function to pretty-print an object with an ability to annotate every value.

API

/**
 * @typedef {Object} optionsType
 * @property {string} indentTemplate String used to indent one level of code (default: '    ').
 * @property {valueIndex|null} valueIndex A function used to index values in the object, the line of declaration in the output and the internal type of the value.
 */
 
/**
 * @param {Object} subject 
 * @param {optionsType} options 
 * @returns {string} 
 */
prettyPrintObject;

Use

import prettyPrintObject from 'pretty-print-object';

Format Object for `console.log`

console.log(prettyPrintObject({
    foo: 'FOO',
    bar: 'BAR',
    emptyArray: [],
    emptyObject: {},
    arrayWithLiteralValues: [
        1,
        2,
        3
    ],
    objectWithLiteralValues: {
        1: 'foo',
        2: 'bar',
        3: 'baz',
    },
    types: [
        undefined,
        null,
        function (a, b) {},
        (a, b) => {},
        NaN,
        Infinity,
        10.2,
        true
    ]
}));

{
    foo: "FOO",
    bar: "BAR",
    emptyArray: [],
    emptyObject: {},
    arrayWithLiteralValues: [
        1,
        2,
        3
    ],
    objectWithLiteralValues: {
        1: "foo",
        2: "bar",
        3: "baz"
    },
    types: [
        undefined,
        null,
        function (a, b) { ... },
        (a, b) => { ... },
        NaN,
        Infinity,
        10.2,
        true
    ]
}

Annotate Value Types

This library provides a method createValueIndex.

import {
    createValueIndex
} from './../prettyPrintObject';

createValueIndex is a factory function that will produce an instance of valueIndex. valueIndex object implements methods add and increment. These methods are used internally to keep track of where and what values are added to the formatted object string.

getValueIndexData method returns an object describing the collected data, e.g.

{
    1: {
        path: [
            'foo'
        ]
        value: 'foo',
        type: 'string'
    }
}

For this example, we are going to build a helper function formatAnnotatedObject that formats object output, indexes object values and annotates the formatted output with value types.

import _ from 'lodash';
import prettyPrintObject, {
    createValueIndex
} from './../prettyPrintObject';
 
let formatAnnotatedObject;
 
formatAnnotatedObject = (subject) => {
    let formattedValue,
        valueIndex,
        valueIndexData;
 
    valueIndex = createValueIndex();
 
    formattedValue = prettyPrintObject(subject, {
        valueIndex: valueIndex
    });
    valueIndexData = valueIndex.getValueIndexData();
 
    return formattedValue = _.map(formattedValue.split('\n'), (line, linuNumber) => {
        if (_.has(valueIndexData, linuNumber)) {
            line += ' : ' + valueIndexData[linuNumber].type;
        }
 
        return line;
    }).join('\n');
};

We are going to annotate data from the previous example:

console.log(formatAnnotatedObject({
    foo: 'FOO',
    bar: 'BAR',
    emptyArray: [],
    emptyObject: {},
    arrayWithLiteralValues: [
        1,
        2,
        3
    ],
    objectWithLiteralValues: {
        1: 'foo',
        2: 'bar',
        3: 'baz',
    },
    types: [
        undefined,
        null,
        function (a, b) {},
        (a, b) => {},
        NaN,
        Infinity,
        10.2,
        true
    ]
}));

{
    foo: "FOO", : string
    bar: "BAR", : string
    emptyArray: [], : array
    emptyObject: {}, : object
    arrayWithLiteralValues: [
        1, : number
        2, : number
        3 : number
    ], : array
    objectWithLiteralValues: {
        1: "foo", : string
        2: "bar", : string
        3: "baz" : string
    }, : object
    types: [
        undefined, : undefined
        null, : null
        function (a, b) { ... }, : function
        (a, b) => { ... }, : function
        NaN, : nan
        Infinity, : number
        10.2, : number
        true : boolean
    ] : array
} : object

Install

npm install pretty-print-object