Finding first alphabetical letter in a string - Javascript

Question

I've done some research and can't seem to find a way to do this. I even tried using a for loop to loop through the string and tried using the functions isLetter() and charAt(). I have a string which is a street address for example:

var streetAddr = "45 Church St";

I need a way to loop through the string and find the first alphabetical letter in that string. I need to use that character somewhere else after this. For the above example I would need the function to return a value of C. What would be a nice way to do this?

VisioN · Accepted Answer · 2014-05-13 13:06:39Z

13

Maybe one of the shortest solutions:

'45 Church St'.match(/[a-zA-Z]/).pop();

Since match will return null if there are no alphanumerical characters in a string, you may transform it to the following fool proof solution:

('45 Church St'.match(/[a-zA-Z]/) || []).pop();

answered May 13, 2014 at 13:06

VisioN

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3 Comments

fadim Over a year ago

I must admit after trying this solution, it is the best out of all of them.

RobG Over a year ago

Or '45 Church St'.replace(/^[^a-z]+/ig,'').substr(0,1) avoids the issues with match. Also ('45 Church St'.match(/[a-z]/i) || []).pop() saves 2 characters. :-)

RobG Over a year ago

Oh, there's also '45 Church St'.replace(/^[^a-z]+/ig,'')[0] but IE doesn't like that. :-(

thefourtheye · Accepted Answer · 2014-05-13 13:07:23Z

7

Just check if the character is in the range A-Z or a-z

function firstChar(inputString) {
    for (var i = 0; i < inputString.length; i += 1) {
        if ((inputString.charAt(i) >= 'A' && inputString.charAt(i) <= 'Z') || 
            (inputString.charAt(i) >= 'a' && inputString.charAt(i) <= 'z')) {
            return inputString.charAt(i);
        }
    }
    return "";
}

console.assert(firstChar("45 Church St") === "C");
console.assert(firstChar("12345") === "");

answered May 13, 2014 at 13:07

thefourtheye

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2 Comments

Paul S. Over a year ago

+1 Because OP says I need a way to loop through the string and ...

Matthew Lock Over a year ago

Nothing wrong with this code, and the OP asked for a loop, but it's a great example of why regexes are worth the initial pain of learning.

Paul S. · Accepted Answer · 2014-05-13 13:06:43Z

6

This can be done with match

"45 Church St".match(/[a-z]/i)[0]; // "C"

answered May 13, 2014 at 13:06

Paul S.

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3 Comments

fadim Over a year ago

I've never used match before, where does the "C" value go to?

Paul S. Over a year ago

Currently it's not "going" anywhere, the line evaluates to it. You can use an = or a return or whatever you want to access it elsewhere

VisioN Over a year ago

Though there will be another problem if the source string doesn't have any alphanumerical characters.

Jay Lepore · Accepted Answer · 2020-01-23 00:47:51Z

0

This code example should get the job done.

function numsNletters(alphanum) {
    firstChar=alphanum.match(/[a-zA-Z]/).pop();
    numsLetters=alphanum.split(firstChar);
    numbers=numsLetters[0];
    // prepending the letter we split on (found with regex at top)
    letters=firstChar+numsLetters[1];
    return numbers+'|'+letters;
}

numsNletters("123abc"); // returns "123|abc";

answered Jan 23, 2020 at 0:47

Jay Lepore

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