Finding the index to a non-specified character

Question

Let's say for example I have a string

thisIsThisTuesday Day

I want to find the index of all the capital letters, test if there is a space before it, and if not insert one. I would need the index of each one. At least from what I can see indexOf(String) will only produce the index of the first occurance of the character T/t

This :

for(i=0;i<str.length;i++){
  let char=str[i];

  if(isNaN(char*1)&&char==char.toUpperCase()){
    y=str.indexOf(char);
    console.log(char,y)
  }
}

would produce the capital letters, and their indexes but will only display the first occurrence of the character in question. I feel pretty confident that the part I am missing is a for() loop in order to move the index iteration..but it escapes me.

Thank you in advance!

Maybe not a direct dupe but you can probably use the approach that answers the following question. https://stackoverflow.com/questions/6055152/finding-uppercase-characters-within-a-string — SamuelB, Dec 10 '18 at 11:15
Possible duplicate of [Finding uppercase characters within a string](https://stackoverflow.com/questions/6055152/finding-uppercase-characters-within-a-string) — TessavWalstijn, Dec 10 '18 at 11:15

score 2 · Answer 1 · edited Dec 10 '18 at 11:51

2

You can use a regex:

It matches any non-whitespace character followed by a capital letter and replaces it by the two characters with a space between.

const str = "thisIsThisTuesday Day";
const newstr = str.replace(/([^ ])([A-Z])/g, "$1 $2");
console.log(newstr);

edited Dec 10 '18 at 11:51

georg

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answered Dec 10 '18 at 11:22

Sebastian Speitel

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It would be cleaner to use groups and group references (`$1`) in your replacement. – georg Dec 10 '18 at 11:39
Yes but I wasn't sure about that, you can edit my answer if you want to – Sebastian Speitel Dec 10 '18 at 11:49

Nick Parsons · Answer 2 · 2018-12-10T12:13:13.697

1

You can use the following regular expression:

/(?<=\S)(?=[A-Z])/g

The replace will insert spaced between characters which are non-space followed by a capital letter.

See example below:

let str = "thisIsThisTuesday Day";
const res = str.replace(/(?<=\S)(?=[A-Z])/g, ' ');

console.log(res);

Note: As pointed out ?<= (positive lookbehind) is currently not be available in all browsers.

edited Dec 10 '18 at 12:13

answered Dec 10 '18 at 11:21

Nick Parsons

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Yup , sorry about not looking into the regex. ywc – Arunprasanth K V Dec 10 '18 at 11:30
NB: lookbehind assertions are ES2018, and not universally supported yet. – georg Dec 10 '18 at 11:36
@georg ah, yes. Thanks for pointing this out. I've edited my answer – Nick Parsons Dec 10 '18 at 11:39
Regex has always been an achilles heal for me. But ultimately is much more efficient I believe.. and I think now that you have been so kind as to point that out so blatently for me.( in a good way) I really need to hone that skill a bit further.. – BrBearOFS Dec 11 '18 at 10:50
Thank you all for your time and effort in assisting with this ! – BrBearOFS Dec 11 '18 at 10:50
@BrBearOFS no worries, I don’t claim to be an expert in regex either, I just know a few basics because it is an incredibly powerful tool, and having the basics can allow you to do complex things like this rather easily. All it takes is a little bit of practice :) – Nick Parsons Dec 11 '18 at 10:53

Alex G · Answer 3 · 2018-12-10T11:48:41.783

You could iterate over the string and check if each character is a capital. Something like this:

const s = 'thisIsThisTuesday Day';

const format = (s) => {
    
    let string = '';

    for (let c of s) {

        if (c.match(/[A-Z]/)) string += ' ';

        string += c;
    }

    return string;
};

console.log(format(s));

Or alternatively with reduce function:

const s = 'thisIsThisTuesday Day';

const format = (s) => s.split('').reduce((acc, c) => c.match(/[A-Z]/) ? acc + ` ${c}` : acc + c, '');

console.log(format(s));

score 0 · Accepted Answer · edited Dec 10 '18 at 11:37

0

Actually, the String.indexOf function can take a second argument, specifying the character it should start searching from. Take a look at: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/String/indexOf

But, if you just want to find all capital letters and prefix them with a space character, if one is not found, there are many approaches, for example:

var str = "thisIsThisTuesday Day";
var ret = '';
for (var i=0; i<str.length; i++) {
    if (str.substr(i, 1) == str.substr(i, 1).toUpperCase()) {
        if ((i > 0) && (str.substr(i - 1,1) != " "))
            ret += " ";
    }
    ret += str.substr(i,1);
}

After running this, ret will hold the value "this Is This Tuesday Day"

edited Dec 10 '18 at 11:37

georg

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answered Dec 10 '18 at 11:34

Spyros P.

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please use MDN for JS documentation references. – georg Dec 10 '18 at 11:38
Thank you.. this was what I was seeking originally. I appreciate the hand ! – BrBearOFS Dec 11 '18 at 10:47

Finding the index to a non-specified character

4 Answers4