javascript - 我听不懂这部分：“（obj [val] || 0）+1;” [重复](I can't understand this part: “(obj[val] || 0)+1;” [duplicate])

Question

(This question already has answers here) :

((这个问题已经在这里有了答案)

：)

Understanding the use of ||

(了解||的用法)

in the code [duplicate] (4 answers)

(在代码中[重复] （4个答案）)

What is the purpose of “x = x ||

(“ x = x ||”的目的是什么)

0”?

(0”？)

[duplicate] (6 answers)

([重复] （6个答案）)

What does the construct x = x ||

(x = x ||的构造是什么)

y mean?

(你的意思是？)

(11 answers)

(（11个答案）)

Closed 10 hours ago .

(10小时前关闭。)

 let arr = [1, 2, 3, 2, 3], obj = {}; for (let val of arr) { obj[val] = (obj[val] || 0) + 1; } console.log(obj); 

Output should be:

(输出应为：)

obj = {
  1: 1,
  2: 2,
  3: 3
}

  ask by Karunamay Murmu translate from so

Answer 1

等待大神答复