Combining regular expressions in Javascript

Question

Is it possible to combine regular expressions in javascript.

For ex:

 var lower = /[a-z]/;  var upper = /[A-Z]/;  var alpha = upper|lower;//Is this possible? 

ie. can i assign regular expressions to variables and combine those variables using pattern matching characters as we do in regular expressions

Answer 1

The answer is yes! You have to initialize the variable under the RegExp class:

var lower = new RegExp(/--RegexCode--/); var upper = new RegExp(/--RegexCode--/); 

hence, regex can be dynamically created. After creation:

"sampleString".replace(/--whatever it should do--/); 

Then you can combine them normally, yes.

var finalRe = new RegExp(lower.source + "|" + upper.source); 

Answer 2

If regexps are not known beforehand,

var one = /[a-z]/; var two = /[A-Z]/;  var one_or_two = new RegExp("(" + one.source + ")|(" + two.source + ")")