Help us understand the problem. What is going on with this article?

underscoreコードリーディング(defaults)

More than 3 years have passed since last update.

underscoreに詳しくないので、勉強半分でソースコードを読む。

利用するバージョン

underscore.js(v1.8.3)

defaultsとは

underscorejs.orgのdefaults

こんな説明。

_.defaults(object, *defaults)

Fill in undefined properties in object with the first value present in the following list of defaults objects.

var iceCream = {flavor: "chocolate"};
_.defaults(iceCream, {flavor: "vanilla", sprinkles: "lots"});
=> {flavor: "chocolate", sprinkles: "lots"}


defaults objectsに指定されている値で、オブジェクトのundefinedなプロパティを埋めます。

underscore.defaults

コード的にはこのあたり。

  // Fill in a given object with default properties.
  _.defaults = createAssigner(_.allKeys, true);

createAssignerに.allKeysとtrueを渡す。
createAssigner_.extendで説明したとおり、objectを引数にとる関数で、
.allKeysの結果を用いて、obj[key] === void 0なところに値を埋める。

ikasumi_wt
なんでもやるエンジニア。 名古屋 -> 東京 JavaScript/PHP周り。 最近:Laravel/Node.js/Electron/Vue.js/React.js。 その他:Heroku,IBM Bluemix
http://ikasumiwt.hatenadiary.jp/
Why not register and get more from Qiita?
  1. We will deliver articles that match you
    By following users and tags, you can catch up information on technical fields that you are interested in as a whole
  2. you can read useful information later efficiently
    By "stocking" the articles you like, you can search right away
Comments
No comments
Sign up for free and join this conversation.
If you already have a Qiita account
Why do not you register as a user and use Qiita more conveniently?
You need to log in to use this function. Qiita can be used more conveniently after logging in.
You seem to be reading articles frequently this month. Qiita can be used more conveniently after logging in.
  1. We will deliver articles that match you
    By following users and tags, you can catch up information on technical fields that you are interested in as a whole
  2. you can read useful information later efficiently
    By "stocking" the articles you like, you can search right away
ユーザーは見つかりませんでした