Regex Javascript Match string by first two characters

Question

I have to match a string by it's first two letters using Regex to check a specific two characters available as the first two letters of a string. Here assume that the first two characters are 'XX'.

And the strings I need to match are

ABCDS
XXDER
DERHJ
XXUIO

So I need to filter this list to get strings that only starts with 'XX'

code I tried so far

var filteredArr = [];
var arr = [ "ABCDS ", "XXDER ", "DERHJ ", "XXUIO" ];
var re = new RegExp('^[a-zA-Z]{2}');
jQuery.each( arr, function( i, val ) {

if(re.test(val )){
  filteredArr.push(val);
}
});

What will be the exact Regex pattern to check the string that starts with 'XX'

I recommend you these tools to avoid headaches : regex101.com & txt2re.com — Maen
– Maen, Commented May 17, 2016 at 10:13

gurvinder372 · Accepted Answer · 2016-05-17 10:15:03Z

7

simply try

var filteredMatches = arr.filter(function(val){
  return val.indexOf("XX") == 0;
});

answered May 17, 2016 at 10:15

gurvinder372

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Comments

Jed Fox · Accepted Answer · 2016-12-10 22:59:16Z

4

You can simply use JavaScript .startsWith() method.

var arr = [ "ABCDS ", "XXDER ", "DERHJ ", "XXUIO" ];

var filteredArr = arr.filter(function(val){
  return val.startsWith("XX");
});

console.log(filteredArr);

edited Dec 10, 2016 at 22:59

Jed Fox

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answered May 17, 2016 at 10:31

Munawir

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Comments

jcubic · Accepted Answer · 2016-05-17 10:16:02Z

2

Try this:

var arr = [ "ABCDS ", "XXDER ", "DERHJ ", "XXUIO" ];
// match if two letters at the beginning are the same
var re = new RegExp('^([a-zA-Z])\\1');
var filteredArr = arr.filter(function(val) {
  return re.test(val);
});
document.body.innerHTML = JSON.stringify(filteredArr);

answered May 17, 2016 at 10:16

jcubic

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Comments

Atal Kishore · Accepted Answer · 2016-05-17 10:18:08Z

1

 var filteredArr = [];
 var arr = [ "ABCDS ", "XXDER ", "DERHJ ", "XXUIO" ];
 var re = new RegExp('^XX');
 jQuery.each( arr, function( i, val ) {

 if(re.test(val )){
 filteredArr.push(val);
 }
});

^ means match at the beginning of the line

answered May 17, 2016 at 10:18

Atal Kishore

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Comments

Andy · Accepted Answer · 2016-05-17 10:18:05Z

0

Use filter with a less-complex regex:

var filtered = arr.filter(function (el) {
  return /^X{2}/.test(el);
});

DEMO

answered May 17, 2016 at 10:18

Andy

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Comments

Jed Fox · Accepted Answer · 2016-12-10 23:02:11Z

0

I suggest string match :

var arr = [ "ABCDS ", "XXDER ", "DERHJ ", "XXUIO" ];

var r = arr.filter(x => x.match(/^XX/))

console.log(r)

edited Dec 10, 2016 at 23:02

Jed Fox

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answered May 17, 2016 at 10:17

maioman

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