WaldoJS

I got frustrated looking for specific properties and values within JavaScript object trees — so I created a utility to do it for me.

Waldo lets you search globally or within specificied objects. You can search by property name, property type or property value. You can also create your own custom search functions. Waldo can be run as an npm module, or a global file and there's also an autogenerated bookmarklet you can use for quick checks in the console.

Overview

A waldo search returns an array of Match objects...

var waldo = require('waldojs');
 
// find react properties named 'oneOfType'
var React = require('react');
var matches = waldo.byName('oneOfType', React);  
 
matches[0].path; // 'SRC.PropTypes.oneOfType'
matches[0].value; // [the function]
matches[0].type; // 'function'

Running log over a Match, or all matches, returns a formatted text summary.

// global search for objects with a value of 10
waldo.byValue(10).log(); // =>
  GLOBAL.module.exports.repl._maxListeners -> (number) 10
  GLOBAL.module.exports.repl.rli._maxListeners -> (number) 10
  GLOBAL.module.exports.repl.outputStream._maxListeners -> (number) 10
  GLOBAL.module.exports.repl.inputStream._maxListeners -> (number) 10

If you use a transpiler like babel you could interact with waldo in ES 6. (Waldo is itself written in ES 6).

// use a destructure assignment to find a nested pattern
const obj = {a: {a: 3, b: {c: 4, a: {a: {b: 4}}}}};
const matches = find.custom(
  (what, obj, prop) => {
  let {a: {b: x}} = obj[prop];
  return x === 4;
}, obj);
matches.log(); // 'SRC.a.b.a -> (object) {a: {b: 4}}'

Installation and Usage

1. Using the npm module

npm install waldojs

then

var waldo = require('waldojs'); // ES 5

or

import  waldo  from 'waldojs'; // ES 6

2. Standalone

Clone this repo and run make to generate the standalone bundles waldobundle.js and waldobundle.min.js. The global waldo object will now be available to you.

3. Using the Bookmarklet in the Browser Console

By using the supplied bookmarklet (lib/bookmarklet.txt - you'll need to run make if it isn't there) you can type waldo commands directly in the console. When run in the console waldo auto-logs all matches.

Output

Match

Every time waldo finds an object that matches the search criteria, a Match object is created. Each call to waldo returns an array of Match objects.

A Match instance has the following properties

• path the property path to reach the matching object.
• prop the name of the matching object.
• value the value of the matching object.
• obj the matching object
• log function that returns a formatted string representation of the match (the array of matches also has a log function that returns a formatted string of all matches).

API

Waldo accepts a variety of query methods.

• byName search the object tree for properties with this name
• byValue search the object tree for properties with this value
• byValueCoerced search the object tree for properties that == this value
• byType search the object tree for properties that are an instance of the given class/constructor.
• custom supply a custom search function

Each method accepts up to 2 arguments:

• what (required) the property, value or type to match on
• where (optional - default is the global object) the root of the search

byName

// Find properties named 'read' anywhere
var matches = waldo.byName('read');
matches.length; // 1
matches[0].value; // [the function]
matches[0].log(); // =>
  'GLOBAL.module.exports.repl.inputStream.read -> (function) [object Function]'

byValue

// Global search for all properties with the value 10
var matches = waldo.byValue(10);
matches.length // => 4;
 
// return the results as a formatted string...
// (when running globally these logs appear in the console by default)
matches.log(); // =>
  GLOBAL.module.exports.repl._maxListeners -> (number) 10
  GLOBAL.module.exports.repl.rli._maxListeners -> (number) 10
  GLOBAL.module.exports.repl.outputStream._maxListeners -> (number) 10
  GLOBAL.module.exports.repl.inputStream._maxListeners -> (number) 10

byValueCoerced

// get all falsey values globally
waldo.byValueCoerced(false); // =>
  GLOBAL.deviceIsAndroid -> (boolean) false
  GLOBAL.deviceIsIOS -> (boolean) false
  GLOBAL.defaultstatus -> (string) ''
  GLOBAL.GitHub.support.setImmediate -> (boolean) false
  GLOBAL.chrome.app.isInstalled -> (boolean) false
  etc..

byType

var a = {
  aa: ['x', 'y', 'z'],
  bb: {
    bbb: [1, 2, 3],
    ccc: 54
  }
};
 
waldo.byType(Array, a); // =>
  SRC.aa -> (object) x,y,z
  SRC.bb.bbb -> (object) 1,2,3

Custom

The custom method takes 2 arguments:

• fn - function specifying match criteria
• where (optional) -where to search

// find all true values beginning with 'c'
var vegetables = {
  carrots: {
    chopped: false,
    cleaned: true
  }
  leaks: {
    chopped: true,
    cleaned: false
  }
};
 
waldo.custom(function(what, obj, prop) {
  return (obj[prop] === true) && (!prop.indexOf('c'));
}, vegetables); // =>
  SRC.leaks.chopped -> (boolean) true
  SRC.carrots.cleaned -> (boolean) true

Circular References

Waldo detects circular references and cites them:

var a = {x: b};
var b = {y: c};
var c = {z: a};
waldo.byName('z');

will log...

GLOBAL.c.z -> (<GLOBAL.a>) {z: a}

Thanks to John-David Dalton for adding circular reference detection as well as providing some early refactor commits.

Testing

To test both module and the standalone bundles:

npm test

To run continuous tests in watch mode:

npm run testc