获取单词中重复次数最多的字母的计数

本文介绍了获取单词中重复次数最多的字母的计数的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！ 问题描述

我正在尝试计算单词中重复次数最多的字母

I am trying to get the count of the most repeated letter in a word

function GreatestCount(str) { var count = {} for (var i = 0 ; i<str.length;i++) { var char = str[i]; count[char] = (count[char] || 0) + 1; } //get the largest number for the letter counts var max = 0; for (var c in count) { if (count[c] > max) max = count[c]; } return max }

有人可以向我解释为什么

can someone explain to me why

count[char] = (count[char] || 0) + 1;// this works count[char] += 1 // this does not work

推荐答案

因为

count[char] += 1

等于

count[char] = count[char] + 1

第一次运行代码时，count[char]是undefined，因此它与

and the first time the code is run, count[char] is undefined so it's pretty much the same as

undefined + 1 // which is NaN

工作版本通过使用||运算符安全地添加0来避免这种情况.

The working version circumvents this case by safely adding with 0 using || operator.