Qiita Teams that are logged in
You are not logged in to any team

Log in to Qiita Team
Community
OrganizationAdvent CalendarQiitadon (β)
Service
Qiita JobsQiita ZineQiita Blog
Help us understand the problem. What is going on with this article?

ショートカット演算

More than 3 years have passed since last update.

・JavaScriptでは、論理演算子の時
    ・空白文字数値の0null、undefined
 の時はfalseとみなされます。
   

name変数は空白文字falseとみなされます。
右側は空白文字、数値の0、nullでないため日本太郎はtrueとみなされ代入されます。
よって日本太郎と表示されます。

name.js
var name = '';
name = name || '日本太郎';

console.log(msg);      // 結果 日本太郎
konson78960
二進数になりたい
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