JavaScript equivalent of Python's rsplit

Question

str.rsplit([sep[, maxsplit]])

Return a
list of the words in the string, using
sep as the delimiter string. If
maxsplit is given, at most maxsplit
splits are done, the rightmost ones.
If sep is not specified or None, any
whitespace string is a separator.
Except for splitting from the right,
rsplit() behaves like split() which is
described in detail below.

http://docs.python.org/library/stdtypes.html#str.rsplit

Asked By: Jesse Aldridge

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Source

Answer 1

Assuming the semantics of JavaScript split are acceptable use the following

String.prototype.rsplit = function (delimiter, limit) {
  delimiter = this.split (delimiter || /s+/);
  return limit ? delimiter.splice (-limit) : delimiter;
}

Answered By: HBP

Answer 2

String.prototype.rsplit = function(sep, maxsplit) {
    var split = this.split(sep);
    return maxsplit ? [ split.slice(0, -maxsplit).join(sep) ].concat(split.slice(-maxsplit)) : split;
}

This one functions more closely to the Python version

“blah,derp,blah,beep”.rsplit(“,”,1) // [ ‘blah,derp,blah’, ‘beep’ ]

Answered By: Morgan ARR Allen

Answer 3

You can also use JS String functions split + slice

Python:

'a,b,c'.rsplit(',' -1)[0] will give you 'a,b'

Javascript:

'a,b,c'.split(',').slice(0, -1).join(',') will also give you 'a,b'

Answered By: Rushabh Mehta

Answer 4

i think this is more "equivalent" until a bug is found, "close" is not acceptable for an answer.

String.prototype.rsplit = function(sep, maxsplit) {
    var result = []
    if ( (sep === undefined) ) {
        sep = " "
        maxsplit = 0
    }

    if (maxsplit === 0  )
        return [this]

    var data = this.split(sep)


    if (!maxsplit || (maxsplit<0) || (data.length==maxsplit+1) )
        return data

    while (data.length && (result.length < maxsplit)) {
        result.push( data.pop() )
    }
    if (result.length) {
        result.reverse()
        if (data.length>1) {
            return [data.join(sep), result ]
        }
        return result
    }
    return [this]
}

Answered By: Pmp P.

JavaScript equivalent of Python's rsplit

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