How to Split my String in Javascript for special case

Question

i want my string using "," (comma) but my String have some special case please help me

input : a,"d,e,f",g //string in csv`

     var myarray=str.spilt(",");

output: myarray[0] = a ,myarray[1]="d ,myarray[3]=e,myarray[4]=f.....

required output : myarray[0] =a ,myarray[1]="d,e,f",myarray[2] = g

please help me... thanks

Answer 1

A small non regex, iterative and slow approach:

var result = [], tmp="", inString = false;
str.split("").forEach(function(char){
  inString = inString != (char === '"');
   if( !inString && char === "," ){
     result.push(tmp);
     tmp = "";
    }else{
     tmp+=char;
    }
});
result.push(tmp);

In action

You may also use a regular for loop instead of the forEach:

for(char of str){ /*...*/ }

However, thats up to you.

Answer 2

This would be a lot smoother with a mapcat operator in JS.

let input = 'a,"d,e,f",g'
var result = []
input.split('"').forEach((e, i) => {
    result = result.concat( i % 2 == 0 ? e.split(',') : e )
})
result = result.filter(e => e != "")

As ChristianFigueroa pointed out: This won't work for cases where the quotes don't surround the whole field: value,val"ue", "value"

However if that is not important for you: jsperf/speedtest

Answer 3

Strongly advise to parse CSV with a tested CSV-parser library instead of any regex.

CSV-parsers for JavaScript

Among the common ones example:

• Papa Parse
• JQuery-CSV
• D3.js DSV module, including a CSV parser

Example usages

Your example using

• .. Papa Parse, can auto-detect the delimiter and has already a default for quoted-strings: quoteChar: '"' (like yours). Try it online:

var csvInput = 'a,"d,e,f",g';
var results = Papa.parse(csvString);
console.log(results);

Output (copied from console):

{
  data: [
    "a",
    "d,e,f",
    "g"
  ],
  errors: []
  meta: {delimiter: ",", linebreak: "↵", aborted: false, truncated: false, cursor: 11}
}

• .. JQuery-CSV, you can try it online:

var input = 'a,"d,e,f",g';
var result = $.csv.toArray(input);
console.log(result);

// even configurable
$.csv.toArrays(input, {
  delimiter: "\"", // already the default, custom value delimiter character
  separator: ',', // already the default, custom field separator character
});

Output:

[
  "a",
  "d,e,f",
  "g"
]

Disadvantage of regular-expressions for CSV parsing

The regex for CSV-parsing can be either simple like split(',') or long, cumbersome and fragile - catasrophic backracking like described on regular-expressions.info: "A Real Example: Matching CSV Records".

Furthermore:

• a regex is not easy to configure.
• a regex is hard to document, maintain, modularize or extend.

If you still want to try, read

• Ben Nadel (2009): "Ask Ben: Parsing CSV Strings With Javascript Exec() Regular Expression Command"

Related questions

• Example JavaScript code to parse CSV data
• How can I parse a CSV string with JavaScript, which contains comma in data?
• Regex to to parse csv with nested quotes
• How to read data From *.CSV file using javascript?

Answer 4

you need to use regexp

var str = 'a,"d,e,f",g';
console.log(str.split(/,"|",/));

Answer 5

myarray = []
while (str) {
    start = str;
    str = str.replace(/(".*?"|[^",]+|)($|,)/, function(match, group1) {
        myarray.push(group1);
        return "";
    });
    if (str == start) break;
}

The code above goes through the CSV string, adding each value it can to the array myarray. If the value has a " as it's first character (may contain commas), it will match until it reaches the next closing ". Otherwise, the regex will just look for the next comma. If it finds something like a value without a closing ", it will automatically stop and myarray will include all the values up to that point that it failed. Empty values (two adjacent commas) will also work.

Answer 6

You can clean up the CSV with adding delimiters " to create new columns. This is in excel though but I'm not sure how you parse this data so might not work for you. Or str_replace() them and then str.split?