How to export JavaScript array info to csv (on cli

Question

I know there are lot of questions of this nature but I need to do this using JavaScript. I am using Dojo 1.8 and have all the attribute info in array, which looks like this:

[["name1", "city_name1", ...]["name2", "city_name2", ...]]

Any idea how I can export this to CSV on the client side?

Answer 1

I added to Xavier Johns function to also include the field headers if needed, uses jQuery though. The $.each bit will need changing for a native javascript loop

function exportToCsv(filename, rows, headers = false) {
    var processRow = function (row) {
        row = $.map(row, function(value, index) {
            return [value];
        });
        var finalVal = '';
        for (var j = 0; j < row.length; j++) {
            if(i == 0 && j == 0 && headers == true){
                var ii = 0;
                $.each(rows[i], function( index, value ) {
                    //console.log(index);
                    var fieldName = index === null ? '' : index.toString();
                    //console.log(fieldName);
                    var fieldResult = fieldName.replace(/"/g, '""');
                    //console.log(fieldResult);
                    if (fieldResult.search(/("|,|\n)/g) >= 0){
                        fieldResult = '"' + fieldResult + '"';
                    }
                    //console.log(fieldResult);
                    if (ii > 0){
                        finalVal += ',';
                        finalVal += fieldResult;
                    }else{
                        finalVal += fieldResult;
                    }
                    ii++;
                    //console.log(finalVal);
                });
                finalVal += '\n';
                //console.log('end: '+finalVal);
            }
            var innerValue = row[j] === null ? '' : row[j].toString();
            if (row[j] instanceof Date) {
                innerValue = row[j].toLocaleString();
            };
            var result = innerValue.replace(/"/g, '""');
            if (result.search(/("|,|\n)/g) >= 0){
                result = '"' + result + '"';
            }
            if (j > 0){
                finalVal += ',';
                finalVal += result;
            }else{
                finalVal += result;
            }
        }
        return finalVal + '\n';
    };
    var csvFile = '';
    for (var i = 0; i < rows.length; i++) {
        csvFile += processRow(rows[i]);
    }
    var blob = new Blob([csvFile], { type: 'text/csv;charset=utf-8;' });
    if (navigator.msSaveBlob) { // IE 10+
        navigator.msSaveBlob(blob, filename);
    }else{
        var link = document.createElement("a");
        if (link.download !== undefined) { // feature detection
            // Browsers that support HTML5 download attribute
            var url = URL.createObjectURL(blob);
            link.setAttribute("href", url);
            link.setAttribute("download", filename);
            link.style.visibility = 'hidden';
            document.body.appendChild(link);
            link.click();
            document.body.removeChild(link);
        }
    }
}

Answer 2

This is a modified answer based on the accepted answer wherein the data would be coming from JSON.

            JSON Data Ouptut:
             0 :{emails: "SAMPLE Co., [e-mail]"}, 1:{emails: "Another CO. , [e-mail]"}


            JS:
            $.getJSON('yourlink_goes_here', { if_you_have_parameters}, function(data) {
            var csvContent = "data:text/csv;charset=utf-8,";
            var dataString = '';
             $.each(data, function(k, v) {
                dataString += v.emails + "\n";
             });

            csvContent += dataString;

            var encodedUri = encodeURI(csvContent);
            var link = document.createElement("a");
            link.setAttribute("href", encodedUri);
            link.setAttribute("download", "your_filename.csv");
            document.body.appendChild(link); // Required for FF

            link.click();
        });

Answer 3

I use this function to convert an string[][] to a csv file. It quotes a cell, if it contains a ", a , or other whitespace (except blanks):

/**
 * Takes an array of arrays and returns a `,` sparated csv file.
 * @param {string[][]} table
 * @returns {string}
 */
function toCSV(table) {
    return table
        .map(function(row) {
            return row
                .map(function(cell) {
                    // We remove blanks and check if the column contains
                    // other whitespace,`,` or `"`.
                    // In that case, we need to quote the column.
                    if (cell.replace(/ /g, '').match(/[\s,"]/)) {
                        return '"' + cell.replace(/"/g, '""') + '"';
                    }
                    return cell;
                })
                .join(',');
        })
        .join('\n'); // or '\r\n' for windows

}

Note: does not work on Internet Explorer < 11 unless map is polyfilled.

Note: If the cells contain numbers, you can add cell=''+cell before if (cell.replace... to convert numbers to strings.

Or you can write it in one line using ES6:

t.map(r=>r.map(c=>c.replace(/ /g, '').match(/[\s,"]/)?'"'+c.replace(/"/g,'""')+'"':c).join(',')).join('\n')

Answer 4

There you go :

<!doctype html>  
<html>  
<head></head>  
<body>
<a href='#' onclick='downloadCSV({ filename: "stock-data.csv" });'>Download CSV</a>

<script type="text/javascript">  
    var stockData = [
        {
            Symbol: "AAPL",
            Company: "Apple Inc.",
            Price: "132.54"
        },
        {
            Symbol: "INTC",
            Company: "Intel Corporation",
            Price: "33.45"
        },
        {
            Symbol: "GOOG",
            Company: "Google Inc",
            Price: "554.52"
        },
    ];

    function convertArrayOfObjectsToCSV(args) {
        var result, ctr, keys, columnDelimiter, lineDelimiter, data;

        data = args.data || null;
        if (data == null || !data.length) {
            return null;
        }

        columnDelimiter = args.columnDelimiter || ',';
        lineDelimiter = args.lineDelimiter || '\n';

        keys = Object.keys(data[0]);

        result = '';
        result += keys.join(columnDelimiter);
        result += lineDelimiter;

        data.forEach(function(item) {
            ctr = 0;
            keys.forEach(function(key) {
                if (ctr > 0) result += columnDelimiter;

                result += item[key];
                ctr++;
            });
            result += lineDelimiter;
        });

        return result;
    }

    window.downloadCSV = function(args) {
        var data, filename, link;

        var csv = convertArrayOfObjectsToCSV({
            data: stockData
        });
        if (csv == null) return;

        filename = args.filename || 'export.csv';

        if (!csv.match(/^data:text\/csv/i)) {
            csv = 'data:text/csv;charset=utf-8,' + csv;
        }
        data = encodeURI(csv);

        link = document.createElement('a');
        link.setAttribute('href', data);
        link.setAttribute('download', filename);
        document.body.appendChild(link);
        link.click();
        document.body.removeChild(link);
       }
</script>  
</body>  
</html>  

Answer 5

In case anyone needs this for knockout js, it works ok with basically the proposed solution:

html:

<a data-bind="attr: {download: filename, href: csvContent}">Download</a>

view model:

// for the download link
this.filename = ko.computed(function () {
    return ko.unwrap(this.id) + '.csv';
}, this);
this.csvContent = ko.computed(function () {
    if (!this.csvLink) {
        var data = ko.unwrap(this.data),
            ret = 'data:text/csv;charset=utf-8,';

        ret += data.map(function (row) {
            return row.join(',');
        }).join('\n');

        return encodeURI(ret);
    }
}, this);

Answer 6

You can do this in native JavaScript. You'll have to parse your data into correct CSV format as so (assuming you are using an array of arrays for your data as you have described in the question):

const rows = [["name1", "city1", "some other info"], ["name2", "city2", "more info"]];
let csvContent = "data:text/csv;charset=utf-8,";
rows.forEach(function(rowArray){
   let row = rowArray.join(",");
   csvContent += row + "\r\n";
}); 

Then you can use JavaScript's window.open and encodeURI functions to download the CSV file like so:

var encodedUri = encodeURI(csvContent);
window.open(encodedUri);

Edit:

If you want to give your file a specific name, you have to do things a little differently since this is not supported accessing a data URI using the window.open method. In order to achieve this, you can create a hidden <a> DOM node and set its download attribute as follows:

var encodedUri = encodeURI(csvContent);
var link = document.createElement("a");
link.setAttribute("href", encodedUri);
link.setAttribute("download", "my_data.csv");
document.body.appendChild(link); // Required for FF

link.click(); // This will download the data file named "my_data.csv".