Why ?
- Underscore js is nothing but a simple js library that gives a number of js functional programming helpers which can be used in your js code. It works well with your own js libraries like prototypejs, jQuery or backbone.
- Simplifies your code to a good extent. Well defined functional helpers are a great advantage for programming languages like python and ruby. Underscore does the same for JS.
- More importantly, it does not modify any built-in objects to add these methods. In the practical scenario, we use multiple libraries from different authors. It is important that built-in objects are not extended in any of this code to avoid side effects. (An example problem caused by extending Array.prototype add adding methods/properties - http://stackoverflow.com/questions/8859828/javascript-what-dangers-are-in-extending-array-prototype)
- Easy to get started and makes you productive in minutes.
Info -
- Home page - http://underscorejs.org/
- Source code - http://underscorejs.org/docs/underscore.html
- Documentation - http://underscorejs.org/
Important functions -
Underscorejs’s home page has the list of functions it offers and they are faily simple to be followed from here. I am just listing down some of them which i think are cool.
| Category | functions |
|---|---|
| Collection (Array/Object) | each, map, reduce, reduceRight, find, where, findWhere, reject, some, contains, invoke, pluck, max, sortBy, groupBy, countBy |
| Array | first, last, rest, compact, flatten, without, union, intersection, uniq, zip, unzip, lastIndexOf, findIndex, range |
| Objects | keys, allKeys, values, pairs, functions, findKey, extend, pick, omit, clone, has, isEqual, isMatch, isEmpty, isElement, isArray, isObject, isArguments, isFunction, isString, isNumber, isFinite, isBoolean, isDate, isRegExp, isNaN, isNull, isUndefined |
| Functions | bind, partial, memoize, delay, throttle, once, after, before, compose |
| Chaining | chain |
Example -
In case of underscorejs, you ll call all the functions on “_” and pass your Objects/variables as arguments. Note that you need to have underscore.js required in your environment to execute the example below.
describe("A spec using beforeAll and afterAll", function() {
var foo;
beforeAll(function() {
foo = 1;
});
afterAll(function() {
foo = 0;
});
it("sets the initial value of foo before specs run", function() {
expect(foo).toEqual(1);
foo += 1;
});
it("does not reset foo between specs", function() {
expect(foo).toEqual(2);
});
});I would say “Underscore is no big deal and not needed to be a part of your code base if you don’t want. I had written a lot of JS code before finding this and was always comfortable. But once you find this little thing, you ll only realize that it takes a great deal out of your way and makes you happy. Especially, if you know what it means modifying the native objects.”