Object utilities

Clone an object

Recursively clone an object (it creates new Object, Array and Date instances).

const Person = {
    firstName: 'Alan',
    lastName: 'Turing',
    birthday: new Date('1912/06/12'),
    knowledge: ['math', 'logic', 'cryptography'],
    enemies: [
        { name: 'Enigma', year: '1940' },
        { name: 'Homophobia', year: '1954' },
    ],
};

const Person2 = clone(Person);

console.log(Person === Person2); // -> false
console.log(Person.firstName === Person2.firstName); // -> true
console.log(Person.birthday === Person2.birthday); // -> false
console.log(Person.knowledge === Person2.knowledge); // -> false
console.log(Person.knowledge.length === Person2.knowledge.length); // -> true
console.log(Person.enemies[0] === Person2.enemies[0]); // -> false
console.log(Person.enemies[0].name === Person2.enemies[0].name); // -> true

Merge two (or more) objects

Starting from two different objects, the are several methods to merge them. The simplest one is to use the provided merge method.

Example

// plain objects
let package = {
    name: 'proteins',
    version: '1.0.0',
    tags: ['javascript'],
    devDependencies: {
        gulp: '3.5.0',
        karma: '1.3.0',
    },
};
let update = {
    version: '1.1.0',
    author: "Chialab",
    tags: ['utils'],
    devDependencies: {
        gulp: '3.9.0',
        mocha: '3.0.0',
    },
};

Result

let newPackage = merge(package, update);

console.log(newPackage.name);                     // -> "proteins"
console.log(newPackage.version);                  // -> "1.1.0"
console.log(newPackage.author);                   // -> "Chialab"
console.log(newPackage.tags.length);              // -> 1
console.log(newPackage.tags[0]);                  // -> "utils"
console.log(newPackage.tags[1]);                  // -> undefined
console.log(newPackage.devDependencies.gulp);     // -> "3.9.0"
console.log(newPackage.devDependencies.karma);    // -> "1.3.0"
console.log(newPackage.devDependencies.mocha);    // -> "3.0.0"

But you can also specify some configuration and exec the merge with a different algorithm. In order to do that, you need to use the merge.config method to create a new merge function.

Options are:

• mergeObjects: by default, Proteins execs a deep merge between sub-objects. To disable this behaviour set this property to false (it will completely replace the key with the last object found).

Result

let newPackage = merge.config({ mergeObjects: false })(package, update);

console.log(newPackage.name);                     // -> "proteins"
console.log(newPackage.version);                  // -> "1.1.0"
console.log(newPackage.author);                   // -> "Chialab"
console.log(newPackage.tags.length);              // -> 1
console.log(newPackage.tags[0]);                  // -> "utils"
console.log(newPackage.tags[1]);                  // -> undefined
console.log(newPackage.devDependencies.gulp);     // -> "3.9.0"
console.log(newPackage.devDependencies.karma);    // -> undefined
console.log(newPackage.devDependencies.mocha);    // -> "3.0.0"

• joinArrays: by default, Proteins does not handle sub-arrays merging (it replaces with the last array). But if you want to concat sub arrays (without duplicates), set this property to true.

Result

let newPackage = merge.config({ joinArrays: true })(package, update);

console.log(newPackage.name);                     // -> "proteins"
console.log(newPackage.version);                  // -> "1.1.0"
console.log(newPackage.author);                   // -> "Chialab"
console.log(newPackage.tags.length);              // -> 2
console.log(newPackage.tags[0]);                  // -> "javascript"
console.log(newPackage.tags[1]);                  // -> "utils"
console.log(newPackage.devDependencies.gulp);     // -> "3.9.0"
console.log(newPackage.devDependencies.karma);    // -> "1.3.0"
console.log(newPackage.devDependencies.mocha);    // -> undefined

• strictMerge: by default, Proteins adds all new keys to the starting object. If a you want a restricted set of keys and you have to handle untrusted sources, you should set this property to true. Only first-object keys will be merged.

Result

let newPackage = merge.config({ strictMerge: true })(package, update);

console.log(newPackage.name);                     // -> "proteins"
console.log(newPackage.version);                  // -> "1.1.0"
console.log(newPackage.author);                   // -> undefined
console.log(newPackage.tags.length);              // -> 1
console.log(newPackage.tags[0]);                  // -> "utils"
console.log(newPackage.tags[1]);                  // -> undefined
console.log(newPackage.devDependencies.gulp);     // -> "3.9.0"
console.log(newPackage.devDependencies.karma);    // -> "1.3.0"
console.log(newPackage.devDependencies.mocha);    // -> "3.0.0"