Bes

About

Bes is a small library for working with objects without mutation in Javascript. Replacement for the builtin mutating array and object operations are provided, along with a record api for easily creating transformable immutable objects.

Modules

lib/array - 'bes::array'

Replacements for push pop shift unshift splice and reverse that return arrays and do not mutate the input array.

// bes.array.push
var a = [1, 2, 3];
var a1 = bes.array.push(a, 4);

a1; // [1, 2, 3, 4]
a; // [1, 2, 3];

lib/object - 'bes::object'

Setting and deleting properties on an object. Operations return a copy of the object and do not mutate the original.

var o = {x: 3, y: {z: 4}};
var o1 = bes.object.deleteProperty(
    bes.object.setProperty(o, 'w', 3, true),
    'x');

o1; // {'y': {'z': 4}, 'w': 3}
o; // {'x': 3, 'y': {'z': 4}});

lib/record - 'bes/record'

Interface for defining an immutable object with transform setters that return copies of the original without mutation.

// Declare record with no prototype and three properties
var R = bes.record.declare(null, ['a', 'b', 'c']);

// crate instance of record
var x = R.create("g", [43], null); // same as new R("g", [43], null)

x instanceof R; // true
x.a; // "g"
x.b; // [43]
x.c; // null

// Using transform setters
var x1 = x.setA("n").setC(100);
x1.a; // "n"
x1.b; // [43]
x1.c; // 100

x.a; // "g"
x.b; // [43]
x.c; // null

Records can subclass and be subclassed by normal objects and extended to create new records:

var S = bes.record.extend(R, ['d']);

var y = S.create(1, 2, 3, 4).setC(100);
y.a; // 1
y.b; // 2
y.c; // 100
y.d; // 4