我正在尝试构建一个函数来计算某个词在短语中出现的次数。
该函数应包括短语中的单词具有额外的非字母字符和/或行尾字符的情况。
function countWordInText(word,phrase){
var c=0;
phrase = phrase.concat(" ");
regex = (word,/\W/g);
var fChar = phrase.indexOf(word);
var subPhrase = phrase.slice(fChar);
while (regex.test(subPhrase)){
c += 1;
subPhrase = subPhrase.slice((fChar+word.length));
fChar = subPhrase.indexOf(word);
}
return c;
}
问题是对于一个简单的值，比如
phrase = "hi hi hi all hi. hi";
word = "hi"
// OR
word = "hi all";
它返回错误值。
最佳答案
您编写的算法显示您花了一些时间来尝试让它发挥作用。但是，仍然有很多地方不起作用。例如，(word,/W/g) 实际上并没有创建您认为的正则表达式。
还有一个更简单的方法:
function countWordInText (word, phrase) {
// Escape any characters in `word` that may have a special meaning
// in regular expressions.
// Taken from https://stackoverflow.com/a/6969486/4220785
word = word.replace(/[\-\[\]\/\{\}\(\)\*\+\?\.\\\^\$\|]/g, '\\$&')
// Replace any whitespace in `word` with `\s`, which matches any
// whitespace character, including line breaks.
word = word.replace(/\s+/g, '\\s')
// Create a regex with our `word` that will match it as long as it
// is surrounded by a word boundary (`\b`). A word boundary is any
// character that isn't part of a word, like whitespace or
// punctuation.
var regex = new RegExp('\\b' + word + '\\b', 'g')
// Get all of the matches for `phrase` using our new regex.
var matches = phrase.match(regex)
// If some matches were found, return how many. Otherwise, return 0.
return matches ? matches.length : 0
}
countWordInText('hi', 'hi hi hi all hi. hi') // 5
countWordInText('hi all', 'hi hi hi all hi. hi') // 1
countWordInText('hi all', 'hi hi hi\nall hi. hi') // 1
countWordInText('hi all', 'hi hi hi\nalligator hi. hi') // 0
countWordInText('hi', 'hi himalayas') // 1
我在整个示例中添加了注释。希望这可以帮助您入门!
这里有几个学习 Javascript 正则表达式的好地方:
您还可以使用 Regexr 测试您的正则表达式。 .
关于javascript - 计算单词出现的次数，允许特殊字符和换行符，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/45384051/