jQuery / Regex: How to compare string against several substrings

Question

I have a special validation need where I need to check if a string contains ANY out of several substrings like the following list:

I am new to jQuery and the only thing I could think of here is the following which doesn't look good to me:

if(str.indexOf("12") >= 0 || str.indexOf("23") >= 0 || str.indexOf("34") >= 0 || str.indexOf("45") >= 0 || str.indexOf("56") >= 0 || str.indexOf("67") >= 0 || str.indexOf("78") >= 0 || str.indexOf("89") >= 0 || str.indexOf("90") >= 0 || str.indexOf("01") >= 0){
     // do stuff
}

Is there a better way where I can compare a string against multiple substrings, e.g. using Regex or arrays ? In addition, I would also need to count the number of matches for which I didn't find an approach.

Many thanks in advance for any help with this.

Cᴏʀʏ · Accepted Answer · 2015-08-04 18:03:51Z

1

You could convert this to a slightly more maintainable format, without getting into regular expressions. This is one way to use an array to accomplish your goal:

var str = '2042038423408';
// Super-quick one-liner (split here for visibility)
var matchCount = $.grep(['12', '23', '34', '45', '56', '67', '78', '89', '90', '01'], function(num, i) {
    return str.indexOf(num) !== -1;
}).length; // should be 2

<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>

Or you could create some nice little re-usable functions:

var valuesToCheck = ['12', '23', '34', '45', '56', '67', '78', '89', '90', '01'];

// Pure JavaScript
function howManyMatches(testString) {
  var matches = 0;
  for (var valueIndex = 0; valueIndex < valuesToCheck.length; valueIndex++) {
    if (testString.indexOf(valuesToCheck[valueIndex]) !== -1) {
      matches++;
    }
  }
  return matches;
}

// Here's the jQuery version again
function howManyMatches2(testString) {
  return $.grep(valuesToCheck, function(num, i) {
    return testString.indexOf(num) !== -1;
  }).length;
}


// Usage
var letsTest = howManyMatches('282982902090229892');
var letsTest2 = howManyMatches2('282982902090229892');

console.log('JavaScript: ' + letsTest); // 2
console.log('jQuery: ' + letsTest2); // 2

<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>

edited Aug 4, 2015 at 18:03

answered Jun 22, 2015 at 22:11

Cᴏʀʏ

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9 Comments

TaneMahuta Over a year ago

Thanks a lot for this ! I can't run your code snippet here but this looks great ! :) I will accept as soon as I can. Just two final questions: 1) The array input could be anything here correct, also special characters like a question mark ? 2) It looks like this does the opposite of what I need since it returns non-matches - would I just change it to > 0 instead of -1 to get the matches, right ?

Cᴏʀʏ Over a year ago

@TaneMahuta: Yes, any string value should be fine. I just edited with a jQuery version.

TaneMahuta Over a year ago

Thanks for the update ! I just added something to my comment.

Cᴏʀʏ Over a year ago

@TaneMahuta: Sorry, I misread your question. You would want !== -1. I updated my code.

TaneMahuta Over a year ago

Awesome, no worries - thanks so much and the explanations are really helpful too ! I'll go with the jQuery version. :)

|

strah · Accepted Answer · 2015-06-23 10:22:22Z

1

You could use a RegExp. Easy to maintain and pure Javascript (no jQuery):

var string = "20420384213408";
var reg = /12|23|34|45|56|67|78|89|90|01/;
if (string.match(reg)) {
    //do stuff
    console.log(string.match(reg).length);
}

edited Jun 23, 2015 at 10:22

answered Jun 22, 2015 at 23:02

strah

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2 Comments

TaneMahuta Over a year ago

Thanks a lot for this as well ! Will try this too. How would I count the matches here ?

strah Over a year ago

console.log(string.match(reg).length);

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