observe/utils.js

A powerful, pragmatic implementation of the observer pattern for javascript objects and arrays.

// utilities needed by the configuration (excludes dependencies the configs don't need so the webpack bundle is lean)

var path = require('path')


// Overwrites obj1's values with obj2's and adds obj2's if non existent in obj1
// any number of objects can be passed into the function and will be merged into the first argument in order
// returns obj1 (now mutated)
var merge = exports.merge = function(obj1, obj2/*, moreObjects...*/){
    return mergeInternal(arrayify(arguments), false)
}

// like merge, but traverses the whole object tree
// the result is undefined for objects with circular references
var deepMerge = exports.deepMerge = function(obj1, obj2/*, moreObjects...*/) {
    return mergeInternal(arrayify(arguments), true)
}

function mergeInternal(objects, deep) {
    var obj1 = objects[0]
    var obj2 = objects[1]

    for(var key in obj2){
       if(Object.hasOwnProperty.call(obj2, key)) {
            if(deep && obj1[key] instanceof Object && obj2[key] instanceof Object) {
                mergeInternal([obj1[key], obj2[key]], true)
            } else {
                obj1[key] = obj2[key]
            }
       }
    }

    if(objects.length > 2) {
        var newObjects = [obj1].concat(objects.slice(2))
        return mergeInternal(newObjects, deep)
    } else {
        return obj1
    }
}

function arrayify(a) {
    return Array.prototype.slice.call(a, 0)
}