How do I get an array like this

[
    0: [ "first", "value", "1" ],
    1: [ "second", "value", "2" ],
    2: [ "third", "value", "3" ]
]

or even better

[ "first", "value", "1", "second", "value", "2", "third", "value", "3" ]

from the string

"first.value[1].second.value[2].third.value[3]"

relying on a single RegEx.exec() run?

I tried this:

regex = /\.*([\w]+)\.([\w]+)\[([\d]*)\]/g;
var str = "first.value[1].second.value[2].third.value[3]";
result = regex.exec(str);

but I can not get the sub-capturing-groups (like in the first example).

PS - I would like to get the regular expressions for both type of results (flat array or nested arrays)

How do I get an array like this

[
    0: [ "first", "value", "1" ],
    1: [ "second", "value", "2" ],
    2: [ "third", "value", "3" ]
]

or even better

[ "first", "value", "1", "second", "value", "2", "third", "value", "3" ]

from the string

"first.value[1].second.value[2].third.value[3]"

relying on a single RegEx.exec() run?

I tried this:

regex = /\.*([\w]+)\.([\w]+)\[([\d]*)\]/g;
var str = "first.value[1].second.value[2].third.value[3]";
result = regex.exec(str);

but I can not get the sub-capturing-groups (like in the first example).

PS - I would like to get the regular expressions for both type of results (flat array or nested arrays)

• javascript
• regex
• nested
• capturing-group

• 1 Use a loop and build the array dynamically. Something like while ((m=regex.exec(str)) !== null) { arr.push(m[1], m[2], m[3]); ....}; See this demo yielding ["first", "value", "1", "second", "value", "2", "third", "value", "3"] – Wiktor Stribiżew Commented Feb 18, 2016 at 12:39
• I know I can do it manually. But I am curious how to do the same with a single regular expression. – Kamafeather Commented Feb 18, 2016 at 12:40
• Could you clarify the with a single regular expression part? A regex expression cannot create, fill out arrays. There are specific language means for that. A regex expression can just match (or not match) some text. – Wiktor Stribiżew Commented Feb 18, 2016 at 12:44
• I didn't want to use additional iteration structures and just rely on the regex magic! Or, at lease, I wanted to know if it is possible. But either you and Federico Piazza (in the ment to his answer) answered my doubt. Regex is not so magic then! – Kamafeather Commented Feb 18, 2016 at 14:04
• 1 It depends on the language. In Python, there are really cool methods in re and regex modules. It is just JS that is not so magical with regexps and its regexp methods are rather misleading. – Wiktor Stribiżew Commented Feb 18, 2016 at 14:28

5 Answers 5

I'd use split:

var str = "first.value[1].second.value[2].third.value[3]";
var res = str.split(/\]\.?|\[|\./)

If the result from the edit, is what you're after

[ "first", "value", "1", "second", "value", "2", "third", "value", "3" ]

Then you can use a very simple regex.

/(\w+)/g

The cleanest way to achieve the first effect would require some array manipulation, as Regex cannot return nested structures.

You can use the above regex (/(\w+)/g) to get a matched array, and run it through the following:

var finalArr= [];

for (var i= 1, j= 0; i < matched.length; i += 3) {
  finalArr[j] = match.slice(i, 3);
  j++;
}

Following your pattern idea, you can use a regex like this:

(.*?)\.(.*?)\[(\d+)\]\.?

Working demo

Match information

MATCH 1
1.  [0-5]   `first`
2.  [6-11]  `value`
3.  [12-13] `1`
MATCH 2
1.  [15-21] `second`
2.  [22-27] `value`
3.  [28-29] `2`
MATCH 3
1.  [31-36] `third`
2.  [37-42] `value`
3.  [43-44] `3`

string.match(/(\w+)/g) The match method on string can produce an array you are looking for. Just extract the words with \w:

var regex = /(\w+)/g;
var str = "first.value[1].second.value[2].third.value[3]";

var arr = str.match(regex)


document.querySelector('pre').innerHTML = JSON.stringify(arr, 0, 4);

<pre></pre>

You can try in 2 steps, split using the ]. and then next step split using the .

var str = "first.value[1].second.value[2].third.value[3]";
var tempArr  = (str+'.').replace(/\[/g,'.').split('].');
var finalArr = tempArr.map(function(v){return v.split('.');});

//result: [["first", "value", "1"], ["second", "value", "2"], ["third", "value", "3"], [""]]