traversing string in javascript

Question

I have a number of strings concatenated together

"[thing 1,thing 2,cat in the hat,Dr. Suese]"

I would like to traverse this string to stop at a specific comma (given an index) and return the substring immediately after the comma and before the next comma. The problem is I need to do it in JavaScript. I assume it would be something like this

function returnSubstring(i,theString){
    var j,k = 0;
    while(theString.charCodeAt(k) != ','){
        while(i > 0){
            if (theString.charCodeAt(j) == ','){
                i--;
            }
            j++;
        }
        k++;
    }
    return theString.substring(j,k);
}

Is this what it should look like or is there some syntax issue here

Can your data only come in this format? Why not use JSON to serialize the data? — lonesomeday
– lonesomeday, Commented Jan 13, 2014 at 14:16
Do you mean the index of the comma among commas (i.e. the second comma) or the index of the comma in the string (i.e the first comma after the twentieth char) ? — Denys Séguret
– Denys Séguret, Commented Jan 13, 2014 at 14:22

Nandkumar Tekale · Accepted Answer · 2014-01-13 14:34:02Z

2

I would like to traverse this string to stop at a specific comma (given an index) and return the substring immediately after the comma and before the next comma.

--> Let's assume specific index for comma accpeted is 8 i.e. first comma index, you can do :

var givenCommaIndex = 8;
var value = "[thing 1,thing 2,cat in the hat,Dr. Suese]";
var subString = value.substring(givenCommaIndex+1, value.indexOf(",", givenCommaIndex+1));
console.log(subString);

// Output :
"thing 2"

I can write the reusable function like below, it will not just work for comma but other delimiters as well :

function getSubString(str, delimiter, indexOfDelimiter) {
    // TODO : handle specific cases like str is undefined or delimiter is null
    return str.substring(indexOfDelimiter+1, str.indexOf(delimiter, indexOfDelimiter+1));
}

edited Jan 13, 2014 at 14:34

answered Jan 13, 2014 at 14:24

Nandkumar Tekale

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Comments

Denys Séguret · Accepted Answer · 2014-01-13 14:21:22Z

2

You may split :

var token = "[thing 1,thing 2,cat in the hat,Dr. Suese]"
    .slice(1,-1) // remove [ and ]
    .split(',')
    [2]; // the third token

Or use a regular expression :

var token = "[thing 1,thing 2,cat in the hat,Dr. Suese]"
    .match(/([^\]\[,]+)/g)
    [2];

edited Jan 13, 2014 at 14:21

answered Jan 13, 2014 at 14:14

Denys Séguret

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3 Comments

thefourtheye Over a year ago

He wants to input the index of the comma.

Denys Séguret Over a year ago

@thefourtheye This isn't clear for me. I added a question in comment.

wjhplano Over a year ago

@thefoureye my bad. one off mistake. (j+1,j+k-1) i think

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