Convert CSV data into JSON format using Javascript

Question

I have data in CSV format data and want to convert into JSON format using Javascript.

Following are csv format:

[Test.csv] 
id;name;author
integer;string;authors:n
1;To Kill an Angry Bird;1

[authors.csv] 
id;name
integer;string
1;Harper Lee
2;JRR Tolkien
3;William Shakespeare

I want to get all the books with their authors. So please how can I implement it using Javascript.

Answer 1

The below should work for you.

All credit to http://techslides.com/convert-csv-to-json-in-javascript

//var csv is the CSV file with headers
function csvJSON(csv){

  var lines=csv.split("\n");

  var result = [];

  // NOTE: If your columns contain commas in their values, you'll need
  // to deal with those before doing the next step 
  // (you might convert them to &&& or something, then covert them back later)
  // jsfiddle showing the issue https://jsfiddle.net/
  var headers=lines[0].split(",");

  for(var i=1;i<lines.length;i++){

      var obj = {};
      var currentline=lines[i].split(",");

      for(var j=0;j<headers.length;j++){
          obj[headers[j]] = currentline[j];
      }

      result.push(obj);

  }

  //return result; //JavaScript object
  return JSON.stringify(result); //JSON
}

Answer 2

I would check out out PapaParse . They have a file called papaparse.min.js that you can drop into your project if need be. PapaParse has no dependencies.

I have used it myself and can verify it works, is convenient, and is well-documented.

Answer 3

Base on @DelightedD0D, I would add if (!lines[i]) continue so it can ignore any empty line and trailing lines.

function csvJSON(csv) {
    const lines = csv.split('\n')
    const result = []
    const headers = lines[0].split(',')

    for (let i = 1; i < lines.length; i++) {        
        if (!lines[i])
            continue
        const obj = {}
        const currentline = lines[i].split(',')

        for (let j = 0; j < headers.length; j++) {
            obj[headers[j]] = currentline[j]
        }
        result.push(obj)
    }
    return result
}

Answer 4

I think, I have a better solution, this also have one issue ie the values should not contain comma(,). Otherwise it is a best solution.

 // convert csv to json
csvJSON(csvText) {
let lines = [];
const linesArray = csvText.split('\n');
// for trimming and deleting extra space 
linesArray.forEach((e: any) => {
    const row = e.replace(/[\s]+[,]+|[,]+[\s]+/g, ',').trim();
    lines.push(row);
});
// for removing empty record
lines.splice(lines.length - 1, 1);
const result = [];
const headers = lines[0].split(",");

for (let i = 1; i < lines.length; i++) {

    const obj = {};
    const currentline = lines[i].split(",");

    for (let j = 0; j < headers.length; j++) {
    obj[headers[j]] = currentline[j];
    }
    result.push(obj);
}
//return result; //JavaScript object
// return JSON.stringify(result); //JSON
return result;
}

// For Reading CSV File
readCSV(event) {
const reader = new FileReader();
reader.readAsText(event.files[0]);
reader.onload = () => {
    const text = reader.result;
    const csvToJson = this.csvJSON(text);
    console.log(csvToJson);
};
}

Thank you

Answer 5

Here is my try on your SPECIFIC example. I know it is an old question but I have used current methods

 const titlesCsv = `id;name;author integer;string;authors:n 1;To Kill an Mockingbird;1 2;Lord of the Rings;2 3;Hamlet;3` const authorsCsv = `id;name integer;string 1;Harper Lee 2;JRR Tolkien 3;William Shakespeare` const parseCsv = csv => { let lines = csv.split("\\n"); const header = lines.shift().split(";") lines.shift(); // get rid of definitions return lines.map(line => { const bits = line.split(";") let obj = {}; header.forEach((h, i) => obj[h] = bits[i]); // or use reduce here return obj; }) }; const titles = parseCsv(titlesCsv) const authors = parseCsv(authorsCsv) const books = titles.map(title => { return { id: title.id, name: title.name, author: authors.find(author => author.id === title.author).name } }) console.log(books)

Answer 6

I have a similar answer like @DelightedD0D but my code can be used in conjunction with Excel directly (copy and paste from Excel into a textarea).

function csvUpload(csvText){
        //Split all the text into seperate lines on new lines and carriage return feeds
        var allTextLines = csvText.split(/\r\n|\n/);
        //Split per line on tabs and commas
        var headers = allTextLines[0].split(/\t|,/);
        var lines = [];
        var locations = [];

        for (var i=1; i<allTextLines.length; i++) {
            var data = allTextLines[i].split(/\t|,/);

            if (data.length == headers.length) {

            var location = {"device_id":data[0], "address":data[1], "city":data[2]};
            locations.push(location);

            }

        }
        return locations;
    }

This way you can use a CSV that is copied into Excel. Excel will remove the seperators like , and others and will insert newlines etc.

With the my code you can pass everything into a textfield directly from Excel and then use that to create a json.

I have the naming of the fields static here, but you could use @DelightedD0D's code to set the headers dynamically:

 for(var j=0;j<headers.length;j++){
          obj[headers[j]] = currentline[j];
      }

Answer 7

This solution fixed the comma issue.

function csvJSON(text, quoteChar = '"', delimiter = ',') {
    var rows=text.split("\n");
    var headers=rows[0].split(",");

    const regex = new RegExp(`\\s*(${quoteChar})?(.*?)\\1\\s*(?:${delimiter}|$)`, 'gs');
  
    const match = line => [...line.matchAll(regex)]
      .map(m => m[2]) 
      .slice(0, -1); 
  
    var lines = text.split('\n');
    const heads = headers ?? match(lines.shift());
    lines = lines.slice(1);
    
    return lines.map(line => {
      return match(line).reduce((acc, cur, i) => {
        // replace blank matches with `null`
        const val = cur.length <= 0 ? null : Number(cur) || cur;
        const key = heads[i] ?? `{i}`;
        return { ...acc, [key]: val };
      }, {});
    });
  }

var csvtojson = csvJSON(SOME_CSV_DATA);
console.log(csvtojson)