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https://github.com/morganconrad/jstocsv
micro csv writer for javascipt objects
https://github.com/morganconrad/jstocsv
csv csv-writer export javascript-library writestream
Last synced: 19 days ago
JSON representation
micro csv writer for javascipt objects
- Host: GitHub
- URL: https://github.com/morganconrad/jstocsv
- Owner: MorganConrad
- License: mit
- Created: 2020-01-08T22:00:57.000Z (almost 5 years ago)
- Default Branch: master
- Last Pushed: 2023-01-06T02:25:16.000Z (almost 2 years ago)
- Last Synced: 2024-10-30T08:49:27.403Z (2 months ago)
- Topics: csv, csv-writer, export, javascript-library, writestream
- Language: JavaScript
- Homepage:
- Size: 191 KB
- Stars: 1
- Watchers: 2
- Forks: 0
- Open Issues: 5
-
Metadata Files:
- Readme: README.md
- License: LICENSE
Awesome Lists containing this project
README
[](http://travis-ci.org/MorganConrad/JStoCSV)
[](https://github.com/MorganConrad/JStoCSV)
[](https://www.npmjs.org/package/jstocsv)
[](https://snyk.io/test/github/morganconrad/JStoCSV)
[](https://coveralls.io/github/MorganConrad/JStoCSV)
# JStoCSV
A small, versatile, dependency free module to convert an array of JavaScript objects to CSV.
- Handles basic nesting, _e.g._ `field.nested.inAnother` or `myArray[4]`
- Support alternative delimiters (_e.g._ TAB delimted) and end of lines.
- Powerful user function option for "tricky stuff".
## Usage
```js
const labelledFields = [
{ path: "name.given", label: "First Name" }, // example of nested data
{ path: "name.surname", label: "Last Name" }
{ path: "birth_day", label: "Date of Birth" },
...
];
data = [
{ name: { given: "John", surname: "Doe" }, birth_day: "06 March 2003" },
...
]
const jstocsv = new JStoCSV(labelledFields);
jstocsv.stream(data, someWriteableStream); // or
let result = jstocsv.generateString(data);
Output / Result
First Name,Last Name,Date of Birth
John,Doe, 06 March 2003
...
```
## API
### JStoCSV(fields, options) constructor
- fields is usually an array of {}
- path: a string, route to get the data, e.g. "name" or "name.first"
- label: label for header line (defaults to path)
- fn: optional user function to apply afterwards (usually null, see Notes at end)
- fields may be an array of strings
- if so, they are used for the path (and the header label)
- fn option is unavailable
_If fields is not provided, JStoCSV will use all keys from the first data value._
- options
- delimiter defaults to ',', you can use '\t' etc.
- eol defaults to '\n'
- quoteEmpties put quotes around all empty fields
- quoteAll put quotes around all fields
- noHeaderLine don't write out a header line
### generateLines(data)
Creates an array of Strings, one per line of the CSV file.
- data is an array of objects.
### generateString(data, appendEOL)
Joins the lines with the eol character.
- data is an array of objects.
- appendEOL at end (default is false)
Both of those require that all the CSV file fit in memory. If your data is huge, consider
### stream(data, writeStream)
- data is an array of objects.
- writeStream **note:** caller must end() or close() etc...
For the ultimate in control
### reduce(data, reducer, acc)
- data is an array of objects
- reducer(acc, line) called for each line in the csv file
- acc the initial accumulator
For convenience, you can use (see tests)
- _stringReducer();
- _streamReducer()
### Notes, Todos, and Caveats
#### Supplying a user function `fn` in `fields`
This module is short because it just does the basics for output. If you need to "do something very special", supply a user function `fn` to `fields`. For each value, it will be called with
`fn(value, datum, index, array)`
- **value** is the value within datum (as determined by path)
- **datum** is the entire object in the data array
- **index** is the 0-based index of the object within the data array
- **array** is the full data array
For example, in the unit test "userfn", we generate an artificial column based on the difference between successive values in the field `.number`, via
```js
fn: function(val, datum, index, array) {
return index ? val-array[index-1].number : val;
}
```
#### Caveats
- The `_quoteValue()` method is pretty basic. Pathological data may break it.
- a new field, `.splitpath`, will be added to each of the fields you pass in.
### Alternatives. Most are larger.
#### [json-csv](https://www.npmjs.com/package/json-csv)
- works very similarly, even has a user function (caller "filter") but less versatile
#### [simple-csv-writer](https://www.npmjs.com/package/simple-csv-writer-csv-writer)
- works with arrays of **arrays** (not objects)
#### [csv-writer](https://github.com/ryu1kn/csv-writer)
- looks good but more complex.
#### [fast-csv](https://www.npmjs.com/package/fast-csv)
- looks powerful
- the headers are confusing