javascript - 搜索（正则表达式），获取匹配字符串最后一个字符的 position

Question

In javascript, the String.search() returns the position (character index) of the character at the start of the match when there are multiple characters . Meaning, for example, if you try to regex search cde in abcdefghij , it returns 2 (where c is at) and not 4 (where e is at). How do I do this? I wouldn't just take the position, add by a fixed number, and you'll get the last character ( Position + 2 ), that won't work if the match have varying length match.

Answer 1

Use match instead. You can use a capture group to add the length of the match.

const [, group, index] = "abcdfghij".match(/(cde?)/)

/* Make sure results are not undefined */

const lastIndex = index + (group.length - 1);

Answer 2

You could always create your own method.

function indexLastCharacter(string, search_word) {
    let indexFirstCharacter = string.search(search_word);
    return indexFirstCharacter + search_word.length;
}

console.log(indexLastCharacter("abcdefghij", "cde"))
// -> 5

Answer 3

I found out that the lookbehind also works, like (?<=y).*$ will return a position after y .