Convert CSV string to an array without .split()

Question

I am trying to come up with a function that will take any string and output an array of numbers and strings without using .split(). Below are the tests it needs to pass and a function that passes the tests currently. I am curious about how other people would solve this.

function csvParse(inputString) {
   var outputArray = [];
   var inputArray = inputString.split(',');
   for (var i =0; i < inputArray.length; i++) {
     if (!Number.isNaN(+inputArray[i])) {
       outputArray.push(+inputArray[i]);
   } else {
     outputArray.push(inputArray[i].replace(/['"]+/g,'').trim());
   }
   }
   return outputArray;
};

describe('CSV Parse', function() {
  it('should parse a string of integers correctly', function() {
    var input = '3,7,9,1,25';
    var output = [ 3, 7, 9, 1, 25 ];
    expect(csvParse(input)).to.deep.equal(output);
  });
  it('should parse a string of strings correctly', function() {
    var input = '"3","7","9","1","25"';
    var output = ["3", "7", "9", "1", "25"];
    expect(csvParse(input)).to.deep.equal(output);
  });
  it('should parse a string of integers and strings correctly', function() {
    var input = '1, "one", 2, "two", 3, "three"';
    var output = [1, "one", 2, "two", 3, "three"];
    expect(csvParse(input)).to.deep.equal(output);
  });
});

Answer 1

Basic JS solution just replacing the split method as you asked (fiddle here)

function dumbComaSplit(inputString) {
   var strArray = [];
   var tmpStr = "";
   for (var i = 0; i < inputString.length; i++) {
        if (inputString.charAt(i) == ',') {
            strArray.push(tmpStr);
            tmpStr = "";
            continue;
        }
        tmpStr += inputString.charAt(i);
    }
    strArray.push(tmpStr);
    return strArray;
};

function csvParse(inputString) {
   var outputArray = [];
   var inputArray = dumbComaSplit(inputString);
   for (var i =0; i < inputArray.length; i++) {
     if (!Number.isNaN(+inputArray[i])) {
       outputArray.push(+inputArray[i]);
   } else {
     outputArray.push(inputArray[i].replace(/['"]+/g,'').trim());
   }
   }
   return outputArray;
};

Answer 2

If you really really want to parse CSV format without spilt, here is one way you can do it using new ECMAScript 6 Template Strings feature.

The basic is that we replace CSV , with mock ${b} expressions and convert the string to a Template String. Then evaluate it while using tag feature. This will create the array for us.

Here is the fiddle.

function csvParse(inputString) {

     b = null;       //dummy variable

     //Prepare the notation to be a TemplateString. Use var b in a dummy expression
     inputString = "`" + inputString.replace(/,/g, '${b}') + "`";


     //Evaluate. Note that we use a tag function inside the evaluation to create the array
     //We also pass the string as a  Template String to evaluate. This is optional
     fn = new Function(`function tag(inputArray) {
                           return inputArray;
                        } 

                        return tag  ${inputString}  `);


     //Return the array         
     return fn().raw;

};


console.log(csvParse("power,of,es6")); 

split is the way to go. But this is the answer you are looking for.