在快速路由器回调中，Array.includes()始终为false，Array.indexOf()始终为-1，Array.find()始终未定义
我使用了fs.readFile()和fs.readFileSync()来读取“words_alpha.txt”。该文件可在以下网址公开获得：https://raw.githubusercontent.com/dwyl/english-words/master/words_alpha.txt
即使查询test与words_alpha.txt文件行数组中的单词相匹配，JSON也总是以{ includes: false, indexFound: false, found: undefined, forFound: false }作为响应，并使用以下JavaScript代码：
var express = require('express');
var router = express.Router();
var fs = require('fs');
router.get('/test_validation', function(req, res, next) {
const { test } = req.query;
fs.readFile('words_alpha.txt', function(err, data) {
const words = data.toString().split('\n');
const includes = words.includes(test);
const indexFound = words.indexOf(test) > -1;
const found = words.find(word => word === test);
let forFound = false;
for (i in words) {
if (words[i] === test) {
forFound = true;
break;
}
}
res.json({ includes, indexFound, found, forFound });
});
});为什么words.includes(test)、words.indexOf(test)和words.find(word => word === test)找不到任何匹配，甚至无法与for (i in words) if (words[i] === test)匹配？但是“words_alpha.txt”words可以用for (i in words) console.log(words[i])逐个记录，但需要几秒钟才能完成。
回答 1
Stack Overflow用户
发布于 2019-03-21 02:55:02
问题是，您使用的文件具有Windows样式的行尾(CR、LF或\r\n，表示为字符)，并且您正在按Unix样式的行尾(LF或\n)拆分，这会产生不正确的单词数组：
const stringOfWords = "apple\r\nbroccoli\r\ncarrot"; //windows line endings
console.log(stringOfWords)
const words = stringOfWords.split("\n");
console.log(words);
console.log(words.includes("apple"))
或者，您可以仅按Windows行尾拆分，但您可能会冒着代码不适用于Unix行尾的风险：
const stringOfWords = "apple\r\nbroccoli\r\ncarrot"; //windows line endings
console.log(stringOfWords)
const words = stringOfWords.split("\r\n");
console.log(words);
console.log(words.includes("apple"))
或者，您也可以将文件转换为Unix文件结尾，您的代码将无需更改即可工作：
const stringOfWords = "apple\nbroccoli\ncarrot"; //unix line endings
console.log(stringOfWords)
const words = stringOfWords.split("\n");
console.log(words);
console.log(words.includes("apple"))
或者，您可以修剪单词以删除空格，从而能够处理任何一行结尾，但对于大文件来说，这可能是一个潜在的繁重操作：
const stringOfWords = "apple\r\nbroccoli\r\ncarrot"; //windows line endings
console.log(stringOfWords)
const words = stringOfWords.split("\n")
.map(word => word.trim());
console.log(words);
console.log(words.includes("apple"))
或者，对于Windows或Unix行结尾，也可以按正则表达式拆分：
const stringOfWords = "apple\r\nbroccoli\r\ncarrot"; //windows line endings
console.log(stringOfWords)
const words = stringOfWords.split(/\r?\n/);
console.log(words);
console.log(words.includes("apple"))
https://stackoverflow.com/questions/55267877
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