Monday, April 6, 2015

Split string in JavaScript using regular expression

JavaScript has split() method which returns array of the substrings based on the separator character used. But you can also split a string using regular expression.

Say you have a credit card number which you want to split in array of four substrings with each substring consisting of 4 digits. For that you would use the match method of string.

var strValue = "1111222233334444";
var splitValues = strValue.match(/(\d{4})(\d{4})(\d{4})(\d{4})/);

// Start looping array from 1st index position as 0
// index position contains the entire parent string
for (var i=1 ; i<splitValues.length ; i++) {
 // Loop through the elements

Here, you use the match method and pass it the regular expression of (\d{4})(\d{4})(\d{4})(\d{4}) to split it into four equal substrings of four digits each. One thing to remember here is that the string returned here contains the parent string at the 0 index position and then the split substrings start at 1st position.

There is limitation here though — you need to know the number of characters in the string before hand, which might not be the case always.

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