CODEWITHSUNDEEP
javascriptregex
Alex Daro
Alex Daro

Reputation: 429

string matching in javascript / regex

What is the best way to match two strings that contain the same phrase? For example is there a good way to match the following two strings: 

st1 = 'jenissplendidicecreams'
st2 = 'jenisicecream'

What would be the proper regex to match those two strings?

Upvotes: 0

Views: 69

Answers (4)

Nick Bartlett
Nick Bartlett

Reputation: 4975

Lots of ways to do this.

You can just use string methods:

var name = st1.slice(0, st1.indexOf("splendidicecream"));

return name == st2.slice(0, st2.indexOf("icecream"));

Or if you really wanted to use regex:

var nameRe = /.+?(?=splendidicecream)/,
    name = st1.match(nameRe)[0];

return st2.startsWith(name);

Or harder regex:

var nameRe = /.+?(?=splendidicecream)/,
    startsWithNameRe = new RegExp("^" + st1.match(nameRe)[0]);

return startsWithNameRe.test(st2);

Upvotes: 0

RobertoNovelo
RobertoNovelo

Reputation: 3810

I am not quite sure but I think you might be looking for something like this?

var str1 = "I have some words!";
var str2 = "I have some very similar words!";

var min = 5;
var max = 6;

var len = str1.length;

for(var i = 0; i<len; i++)
{
  for(var j = min; j<max; j++) 
  {
    var re = new RegExp(str1.substring(i,j));
    console.log(re);

    //Do something when this returns true??
    console.log(re.test(str2));
  }
}

Upvotes: 1

Downgoat
Downgoat

Reputation: 14361

Problem is that computers have no idea where the words are. Either you could index a whole dictionary or use something that uses a specified distance to get values (if string is str2 and str is str1):

var distance = 8, // Best for your current case
    end      = new RegExp('.{'+distance+'}$', '').exec(string)[0],
    start    = new RegExp('^(.*)'+end+'$', '').exec(string)[1];

function matches (s) {
    return new RegExp('^(?:'+start+').*(?:'+end+')$').test(s);
}

matches(str);

Or you can have to computer guess:

var min = 1, // Adjust depending on acceptance level
    split = string.split('').reverse().map(function (a,i) {
        if ( (i+1) % min === 0) {
            return a + '.*';
        } else {
            return a;
        }
    }).reverse().join(''),
    regex = new RegExp(split, '');

regex.test('jenissplendidicecreams');

Upvotes: 0

user663031
user663031

Reputation:

You need to build a regexp which looks like this:

/.*j.*e.*n.*i.*s.*i.*c.*e.*c.*r.*e.*a.*m.*/

This regexp matches if the string being tested includes all the original characters, in order, but with any arbitrary additional characters in between.

We can build that easily enough by doing

function make_regexp(str) {
    var letters = str.split('');
    letters.push(''), letters.unshift('');
    return new RegExp(letters.join('.*'));
}

> make_regexp('jenisicecream')
< /.*j.*e.*n.*i.*s.*i.*c.*e.*c.*r.*e.*a.*m.*/

Now test if the second string matches:

> make_regexp('jenisicecream').test('jenissplendidicecreams')
< true

Upvotes: 2

Related Questions