CODEWITHSUNDEEP
javascriptstringsplit
bboybeatle
bboybeatle

Reputation: 567

Take specific part of a string by character count

I want to take a user submitted string and use parts of it as different variables. I used this to split the text after every third letter...

var values = value.match(/.{3}|.{1,2}/g);

That gives me a nice array of the string split into 3s:

["658", "856", "878", "768", "677", "896"]

However I realised that isn't what I need. I actually need the first 2 letters (var 1), the next 3 letters (var 2), next 1 letter (var 3) etc. etc.

So I would be essentially splitting them more like this...

["65", "885", "6" .....

I don't really need an array as it will be one long number each time, It could look more like...

var Part1 = Number.(grab first 2 characters)
var Part2 = Number.(grab 3 characters from the 3rd onwards)
var Part3 = Number.(grab 6th character only)

etc.. if you can imagine thats properly coded. I can't find detailed information on the .match method.

Upvotes: 3

Views: 202

Answers (4)

Lee Jenkins
Lee Jenkins

Reputation: 2470

Actually, you can use a regular expression to extract multiple substrings in a single call the the match function. You just need to add parenthesis to your regular expression, like this:

var s = "1234567890";
var s.match(/([0-9]{3})([0-9]{1})([0-9]{2})([0-9]{3})/);
for( var i=0; i<matches.length; ++i ) {
    console.log(matches[i]);
}

Output:

123456789
123
4
56
789

Notice that match returns the entire match as element zero of the returned array. My example regex only extracts nine characters, so that's why there is no zero in the output.

IMHO Regular expressions are worth learning because they give you a powerful and concise way to perform string matching. They work (mostly) the same from one language to another, so you can apply the same knowledge in JavaScript, python, ruby, java, whatever.

For more information about regular expressions in JavaScript, see: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Guide/Regular_Expressions

Upvotes: 0

Zohaib Ijaz
Zohaib Ijaz

Reputation: 22885

I hope this is what you are asking for

var value = "123456789123456789";
var values = [];
while(value.length){
    [2, 3, 1].forEach(function(d){
        values.push(value.substr(0,d));
        value = value.substr(d);
    })
}

This is the output:

values = ["12", "345", "6", "78", "912", "3", "45", "678", "9"]

but value string will be "" at the end of loop, so if you want to reuse it, make a copy of it.

Upvotes: 1

beercohol
beercohol

Reputation: 2587

As @Teemu above suggests, you can just use the substr() or substring() string methods.

For example:

var Part1 = value.substr(0, 2);
var Part2 = value.substr(2, 3);
var Part3 = value.substr(5, 1);

See a JS Fiddle example here: https://jsfiddle.net/xpuv4e5j/

Upvotes: 0

Zakaria Acharki
Zakaria Acharki

Reputation: 67505

You can use .substr() instead of match() :

// grab first 2 characters
"123456789".substr(0, 2);  //return "12"

// grab 3 characters from the 3rd onwards
"123456789".substr(2, 3);  //return "345"

// grab 6th character only
"123456789".substr(5, 1);  //return "6"

Hope this helps.

Upvotes: 2

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