javascript - Using regular expressions to split on = , == , and === separately -

i having trouble code trying split string input , save different lists splitting on = , ==, , === each list splits on corresponding one

var tokenequals = code.split(/[=]/gi); var tokendoubleequals = code.split(/[==]/gi); var tokentrippleequals = code.split(/[===]/gi); 

so if if code "= == ===" each list should have length of 2

but happening is splitting on every = , of them end same amount of 7

i have refined down

var tokenequals = code.split(/\=(?!\=)/); var tokendoubleequals = code.split(/\=\=(?!\=)/gi); var tokentrippleequals = code.split(/\=\=\=/gi); 

the current output is: equals length 4, double equals length 3, , tripple equals length 2

when should equal 1

so triple 1 working fine other 2 not. wondering solution put in regexp fields split on cause them split on correspond amount of equals.

bellow example of code in action returns [3, 2, 1] when want return [1, 1, 1]

var lloccounter = function() {};    lloccounter.prototype.count = function(code) {    var numberoflloc = [];      code = code.trim();        var tokenequals = code.split(/\=(?!\=)/);    var tokendoubleequals = code.split(/\=\=(?!\=)/gi);    var tokentrippleequals = code.split(/\=\=\=/gi);        numberoflloc = [      tokenequals.length - 1, // 4	=      tokendoubleequals.length - 1, // 5	==      tokentrippleequals.length - 1, // 6	===    ]      console.log(numberoflloc)  };    contents = "= == ==="  lloccounter = new lloccounter();  numberoflloc = lloccounter.count(contents);

i suggest using mimicking negative lookbehind technique described in mimicking lookbehind in javascript article.

the idea pre-process symbol(s) need split against can use in split method. suggest using literals _single_ or similar:

code = code.trim().replace(/(=)?=(?!=)/g, function($0, $1){  // pre-process single =     return $1 ? $0 : '_single_'; }); code = code.replace(/(=)?==(?!=)/g, function($0, $1){  // pre-process double =     return $1 ? $0 : '_double_'; }); code = code.replace(/(=)?===(?!=)/g, function($0, $1){    // pre-process triple =     return $1 ? $0 : '_triple_'; });  var tokenequals = code.split("_single_");              // split temp tokens var tokendoubleequals = code.split("_double_"); var tokentrippleequals = code.split("_triple_"); 

so, basically, how works: (=)?=(?!=) contains optional capturing group in front ((=)?) can capture = or empty, = matched (in other 2 patterns, == or === respectively), , no = should follow (thanks negative lookahead (?!=)). inside replace method, callback used analyze match data structure: if group 1 (that optional) matched, means = present before = (or ==, or ===) , not want match = (or == or ===). $1 ? $0 : '_single_' piece of code that: $0 stands whole match (if $1 (i.e. group 1 value) not empty, reinsert text found, else, replace temporary token.

var lloccounter = function() {};    lloccounter.prototype.count = function(code) {    var numberoflloc = [];      code = code.trim().replace(/(=)?=(?!=)/g, function($0, $1){  // pre-process single =  	  return $1 ? $0 : '_single_';    });    code = code.replace(/(=)?==(?!=)/g, function($0, $1){  // pre-process double =  	  return $1 ? $0 : '_double_';    });    code = code.replace(/(=)?===(?!=)/g, function($0, $1){    // pre-process triple =  	  return $1 ? $0 : '_triple_';    });      var tokenequals = code.split("_single_");              // split temp tokens    var tokendoubleequals = code.split("_double_");    var tokentrippleequals = code.split("_triple_");        numberoflloc = [      tokenequals.length - 1, // 4	=      tokendoubleequals.length - 1, // 5	==      tokentrippleequals.length - 1, // 6	===    ]      console.log(numberoflloc)  };    contents = "= == ==="  lloccounter = new lloccounter();  numberoflloc = lloccounter.count(contents);