使用点表示法对变量进行JavaScript连续split（）

Question

I have this variable:

var myVar = "r.object.subobject.variable";

I want to add each of the "levels" of this string to an array. My array would contain:

"r.object"
"r.object.subobject"
"r.object.subobject.variable"

I know I can use JavaScript's split() function with a RegEx, but the one I have keeps returning the whole string. For example, I'm trying:

var myArray = myVar.split(/r[.].+/);

Thus, myArray[0] always comes out as "r.object.subobject.variable" .

How can I make myArray[0] = "r.object" , myArray[1] = "r.object.subobject" , and myArray[2] = "r.object.subobject.variable" ?

Hopefully I'm only misunderstanding how regular expressions work instead of needing to do some kind of contrived recursion or array concatenation by only separating on the periods.

Additional Constraints and Background Information

• The variables I'm checking may have a depth from 1 to an unknown number, so any function should try to determine how many strings to extract. All strings will always start with r. (I have a while loop set up for this, and although it will correctly match for a given depth, the split still fails.)
• This operation will occur on thousands or tens of thousands of strings, so speed matters.
• I know bracket notation is a thing, but I cannot use it for my purposes. (The array elements will eventually go back into a specialized AS3 application that doesn't always play nicely with it.)

Answer 1

Actually, myArray[0] should return an empty string. The expression /r[.].+/ matches the whole string, thus returning everything after and before the match (empty strings). Notice the .+ that matches any char repeated once or more times:

r.object.subobject.variable
--^                       ^      [1]: matched by r[.]
1 |           2           |
  +------------------------      [2]: matched my .+

If you want to split by the dots (" . "), use:

var myArray = myVar.split(/[.]/);

---

EDIT As for the updated question, regex can only match a part of the text once .

To achieve what you're trying to do, the following code should do:

 var myVar = "r.object.subobject.variable"; var mySplit = myVar.split("."); var myArray = Array(); for (i = 2; i <= mySplit.length; i++) { myArray.push(mySplit.slice(0,i).join(".")); } document.write(myArray); 

Answer 2

Try using .split() with RegExp /\\./ , do.. while loop , Array.prototype.slice() , Array.prototype.join() , Array.prototype.splice()

 var myVar = "r.object.subobject.variable"; var arr = myVar.split(/\\./), len = arr.length, i = 0, myArray = []; do { myArray.push(arr.slice(0, i).join(".")); ++i; } while (myArray.length <= len); myArray.splice(0, 2); console.log(myArray); 

Answer 3

I don't think you can do get a nice even break like that with regex, maybe if javasacript supported (?R) but doesn't seem like. You could just split it by dots and then concatenate it.

 function levels(str) { var levels; return str.split('.').reduce(function(acc, level, index) { if(index > 0) { levels = levels + '.' + level acc.push(levels); } else { levels = level; } return acc; }, []); } document.getElementById('results').innerHTML = JSON.stringify(levels('r.object.subobject.variable'), null, '\\t'); 

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