Javascript 和正则表达式：拆分字符串并保留分隔符

Javascript and regex: split string and keep the separator

提问by Milo?

I have a string:

我有一个字符串：

var string = "aaaaaa<br />&dagger; bbbb<br />&Dagger; cccc"

And I would like to split this string with the delimiter <br />followed by a special character.

我想用分隔符<br />后跟一个特殊字符来分割这个字符串。

To do that, I am using this:

为此，我正在使用它：

string.split(/<br \/>&#?[a-zA-Z0-9]+;/g);

I am getting what I need, except that I am losing the delimiter. Here is the example: http://jsfiddle.net/JwrZ6/1/

我得到了我需要的东西，除了我丢失了分隔符。这是示例：http: //jsfiddle.net/JwrZ6/1/

How can I keep the delimiter?

我怎样才能保留分隔符？

采纳答案by Jon

Use (positive) lookaheadso that the regular expression asserts that the special character exists, but does not actually match it:

使用（正）前瞻，以便正则表达式断言特殊字符存在，但实际上并不匹配它：

string.split(/<br \/>(?=&#?[a-zA-Z0-9]+;)/g);

See it in action:

看看它在行动：

var string = "aaaaaa<br />&dagger; bbbb<br />&Dagger; cccc";
console.log(string.split(/<br \/>(?=&#?[a-zA-Z0-9]+;)/g));

回答by jichi

I was having similar but slight different problem. Anyway, here are examples of three different scenarios for where to keep the deliminator.

我遇到了类似但略有不同的问题。无论如何，这里是三个不同场景的示例，用于保留分隔符的位置。

"1、2、3".split("、") == ["1", "2", "3"]
"1、2、3".split(/(、)/g) == ["1", "、", "2", "、", "3"]
"1、2、3".split(/(?=、)/g) == ["1", "、2", "、3"]
"1、2、3".split(/(?!、)/g) == ["1、", "2、", "3"]
"1、2、3".split(/(.*?、)/g) == ["", "1、", "", "2、", "3"]

Warning:The fourth will only work to split single characters. ConnorsFanpresents an alternative:

警告：第四个仅适用于拆分单个字符。ConnorsFan提出了一个替代方案：

// Split a path, but keep the slashes that follow directories
var str = 'Animation/rawr/javascript.js';
var tokens = str.match(/[^\/]+\/?|\//g);

回答by Torsten Walter

If you wrap the delimiter in parantheses it will be part of the returned array.

如果将分隔符包装在括号中，它将成为返回数组的一部分。

string.split(/(<br \/>&#?[a-zA-Z0-9]+);/g);
// returns ["aaaaaa", "<br />&dagger;", "bbbb", "<br />&Dagger;", "cccc"]

Depending on which part you want to keep change which subgroup you match

根据您要保留的部分更改您匹配的子组

string.split(/(<br \/>)&#?[a-zA-Z0-9]+;/g);
// returns ["aaaaaa", "<br />", "bbbb", "<br />", "cccc"]

You could improve the expression by ignoring the case of letters string.split(/()&#?[a-z0-9]+;/gi);

您可以通过忽略字母的大小写来改进表达式 string.split(/()&#?[a-z0-9]+;/gi);

And you can match for predefined groups like this: \dequals [0-9]and \wequals [a-zA-Z0-9_]. This means your expression could look like this.

您可以像这样匹配预定义的组：\dequals[0-9]和\wequals [a-zA-Z0-9_]。这意味着您的表情可能如下所示。

string.split(/<br \/>(&#?[a-z\d]+;)/gi);

There is a good Regular Expression Reference on JavaScriptKit.

JavaScriptKit 上有一个很好的正则表达式参考。

回答by Fry

answered it here also JavaScript Split Regular Expression keep the delimiter

在这里也回答了 JavaScript 拆分正则表达式保留分隔符

use the (?=pattern) lookahead pattern in the regex example

在正则表达式示例中使用 (?=pattern) 前瞻模式

var string = '500x500-11*90~1+1';
string = string.replace(/(?=[$-/:-?{-~!"^_`\[\]])/gi, ",");
string = string.split(",");

this will give you the following result.

这将为您提供以下结果。

[ '500x500', '-11', '*90', '~1', '+1' ]

Can also be directly split

也可以直接拆分

string = string.split(/(?=[$-/:-?{-~!"^_`\[\]])/gi);

giving the same result

给出相同的结果

[ '500x500', '-11', '*90', '~1', '+1' ]

回答by SwiftNinjaPro

I made a modification to jichi's answer, and put it in a function which also supports multiple letters.

我对jichi的回答做了修改，放到了一个也支持多字母的函数中。

String.prototype.splitAndKeep = function(separator, method='seperate'){
    var str = this;
    if(method == 'seperate'){
        str = str.split(new RegExp(`(${separator})`, 'g'));
    }else if(method == 'infront'){
        str = str.split(new RegExp(`(?=${separator})`, 'g'));
    }else if(method == 'behind'){
        str = str.split(new RegExp(`(.*?${separator})`, 'g'));
        str = str.filter(function(el){return el !== "";});
    }
    return str;
};

jichi's answers 3rd method would not work in this function, so I took the 4th method, and removed the empty spaces to get the same result.

jichi 的答案第 3 种方法在此函数中不起作用，因此我采用了第 4 种方法，并删除了空格以获得相同的结果。

edit: second method which excepts an array to split char1 or char2

编辑：除数组之外的第二种方法来拆分 char1 或 char2

String.prototype.splitAndKeep = function(separator, method='seperate'){
    var str = this;
    function splitAndKeep(str, separator, method='seperate'){
        if(method == 'seperate'){
            str = str.split(new RegExp(`(${separator})`, 'g'));
        }else if(method == 'infront'){
            str = str.split(new RegExp(`(?=${separator})`, 'g'));
        }else if(method == 'behind'){
            str = str.split(new RegExp(`(.*?${separator})`, 'g'));
            str = str.filter(function(el){return el !== "";});
        }
        return str;
    }
    if(Array.isArray(separator)){
        var parts = splitAndKeep(str, separator[0], method);
        for(var i = 1; i < separator.length; i++){
            var partsTemp = parts;
            parts = [];
            for(var p = 0; p < partsTemp.length; p++){
                parts = parts.concat(splitAndKeep(partsTemp[p], separator[i], method));
            }
        }
        return parts;
    }else{
        return splitAndKeep(str, separator, method);
    }
};

usage:

用法：

str = "first1-second2-third3-last";

str.splitAndKeep(["1", "2", "3"]) == ["first", "1", "-second", "2", "-third", "3", "-last"];

str.splitAndKeep("-") == ["first1", "-", "second2", "-", "third3", "-", "last"];

回答by Berezh

An extension function splits string with substring or RegEx and the delimiter is putted according to second parameter ahead or behind.

扩展函数用子字符串或正则表达式拆分字符串，并根据前面或后面的第二个参数放置分隔符。

    String.prototype.splitKeep = function (splitter, ahead) {
        var self = this;
        var result = [];
        if (splitter != '') {
            var matches = [];
            // Getting mached value and its index
            var replaceName = splitter instanceof RegExp ? "replace" : "replaceAll";
            var r = self[replaceName](splitter, function (m, i, e) {
                matches.push({ value: m, index: i });
                return getSubst(m);
            });
            // Finds split substrings
            var lastIndex = 0;
            for (var i = 0; i < matches.length; i++) {
                var m = matches[i];
                var nextIndex = ahead == true ? m.index : m.index + m.value.length;
                if (nextIndex != lastIndex) {
                    var part = self.substring(lastIndex, nextIndex);
                    result.push(part);
                    lastIndex = nextIndex;
                }
            };
            if (lastIndex < self.length) {
                var part = self.substring(lastIndex, self.length);
                result.push(part);
            };
            // Substitution of matched string
            function getSubst(value) {
                var substChar = value[0] == '0' ? '1' : '0';
                var subst = '';
                for (var i = 0; i < value.length; i++) {
                    subst += substChar;
                }
                return subst;
            };
        }
        else {
            result.add(self);
        };
        return result;
    };

The test:

考试：

    test('splitKeep', function () {
        // String
        deepEqual("1231451".splitKeep('1'), ["1", "231", "451"]);
        deepEqual("123145".splitKeep('1', true), ["123", "145"]);
        deepEqual("1231451".splitKeep('1', true), ["123", "145", "1"]);
        deepEqual("hello man how are you!".splitKeep(' '), ["hello ", "man ", "how ", "are ", "you!"]);
        deepEqual("hello man how are you!".splitKeep(' ', true), ["hello", " man", " how", " are", " you!"]);
        // Regex
        deepEqual("mhellommhellommmhello".splitKeep(/m+/g), ["m", "hellomm", "hellommm", "hello"]);
        deepEqual("mhellommhellommmhello".splitKeep(/m+/g, true), ["mhello", "mmhello", "mmmhello"]);
    });

回答by Berezh

I've been using this:

我一直在用这个：

String.prototype.splitBy = function (delimiter) {
  var 
    delimiterPATTERN = '(' + delimiter + ')', 
    delimiterRE = new RegExp(delimiterPATTERN, 'g');

  return this.split(delimiterRE).reduce((chunks, item) => {
    if (item.match(delimiterRE)){
      chunks.push(item)
    } else {
      chunks[chunks.length - 1] += item
    };
    return chunks
  }, [])
}

Except that you shouldn't mess with String.prototype, so here's a function version:

除了你不应该弄乱String.prototype，所以这里有一个函数版本：

var splitBy = function (text, delimiter) {
  var 
    delimiterPATTERN = '(' + delimiter + ')', 
    delimiterRE = new RegExp(delimiterPATTERN, 'g');

  return text.split(delimiterRE).reduce(function(chunks, item){
    if (item.match(delimiterRE)){
      chunks.push(item)
    } else {
      chunks[chunks.length - 1] += item
    };
    return chunks
  }, [])
}

So you could do:

所以你可以这样做：

var haystack = "aaaaaa<br />&dagger; bbbb<br />&Dagger; cccc"
var needle =  '<br \/>&#?[a-zA-Z0-9]+;';
var result = splitBy(haystack , needle)
console.log( JSON.stringify( result, null, 2) )

And you'll end up with:

你最终会得到：

[
  "<br />&dagger; bbbb",
  "<br />&Dagger; cccc"
]