Complete Example
SheetJS presents a simple JS interface that works with "Array of Arrays" and "Array of JS Objects". The API functions are building blocks that should be combined with other JS APIs to solve problems.
The discussion focuses on the problem solving mindset. API details are covered in other parts of the documentation.
The goal of this example is to generate a XLSX workbook of US President names and birthdays. Click here to jump to the live demo
Acquire Data
Raw Data
The raw data is available in JSON form. For convenience, it has been mirrored here
The data result is an Array of objects. This is the data for John Adams:
{
"id": { /* (data omitted) */ },
"name": {
"first": "John", // <-- first name
"last": "Adams" // <-- last name
},
"bio": {
"birthday": "1735-10-19", // <-- birthday
"gender": "M"
},
"terms": [
{ "type": "viceprez", /* (other fields omitted) */ },
{ "type": "viceprez", /* (other fields omitted) */ },
{ "type": "prez", /* (other fields omitted) */ }
]
}
Filtering for Presidents
The dataset includes Aaron Burr, a Vice President who was never President!
Array#filter
creates a new array with the desired rows. A President served
at least one term with type
set to "prez"
. To test if a particular row has
at least one "prez"
term, Array#some
is another native JS function. The
complete filter would be:
const prez = raw_data.filter(row => row.terms.some(term => term.type === "prez"));
Reshaping the Array
For this example, the name will be the first name combined with the last name
(row.name.first + " " + row.name.last
) and the birthday will be the subfield
row.bio.birthday
. Using Array#map
, the dataset can be massaged in one call:
const rows = prez.map(row => ({
name: row.name.first + " " + row.name.last,
birthday: row.bio.birthday
}));
The result is an array of "simple" objects with no nesting:
[
{ name: "George Washington", birthday: "1732-02-22" },
{ name: "John Adams", birthday: "1735-10-19" },
// ... one row per President
]
Create a Workbook
With the cleaned dataset, XLSX.utils.json_to_sheet
generates a worksheet:
const worksheet = XLSX.utils.json_to_sheet(rows);
XLSX.utils.book_new
creates a new workbook and XLSX.utils.book_append_sheet
appends a worksheet to the workbook. The new worksheet will be called "Dates":
const workbook = XLSX.utils.book_new();
XLSX.utils.book_append_sheet(workbook, worksheet, "Dates");
Clean up Workbook
The data is in the workbook and can be exported.
There are multiple opportunities for improvement: the headers can be renamed and the column widths can be adjusted. SheetJS Pro offers additional styling options like cell styling and frozen rows.
Changing Header Names (click to show)
By default, json_to_sheet
creates a worksheet with a header row. In this case,
the headers come from the JS object keys: "name" and "birthday".
The headers are in cells A1 and B1. XLSX.utils.sheet_add_aoa
can write text
values to the existing worksheet starting at cell A1:
XLSX.utils.sheet_add_aoa(worksheet, [["Name", "Birthday"]], { origin: "A1" });
Changing Column Widths (click to show)
Some of the names are longer than the default column width. Column widths are
set by setting the "!cols"
worksheet property.
The following line sets the width of column A to approximately 10 characters:
worksheet["!cols"] = [ { wch: 10 } ]; // set column A width to 10 characters
One Array#reduce
call over rows
can calculate the maximum width:
const max_width = rows.reduce((w, r) => Math.max(w, r.name.length), 10);
worksheet["!cols"] = [ { wch: max_width } ];
Export a File
XLSX.writeFile
creates a spreadsheet file and tries to write it to the system.
In the browser, it will try to prompt the user to download the file. In NodeJS,
it will write to the local directory.
XLSX.writeFile(workbook, "Presidents.xlsx");
Live Demo
Run the Demo Locally
- Browser
- NodeJS
- Deno
Save the following script to snippet.html
and open the page. The page must be
hosted (no file:///
access).
https://sheetjs.com/pres.html is a hosted version of the page.
<body>
<script src="https://cdn.sheetjs.com/xlsx-latest/package/dist/xlsx.full.min.js"></script>
<script>
(async() => {
/* fetch JSON data and parse */
const url = "https://sheetjs.com/executive.json";
const raw_data = await (await fetch(url)).json();
/* filter for the Presidents */
const prez = raw_data.filter(row => row.terms.some(term => term.type === "prez"));
/* flatten objects */
const rows = prez.map(row => ({
name: row.name.first + " " + row.name.last,
birthday: row.bio.birthday
}));
/* generate worksheet and workbook */
const worksheet = XLSX.utils.json_to_sheet(rows);
const workbook = XLSX.utils.book_new();
XLSX.utils.book_append_sheet(workbook, worksheet, "Dates");
/* fix headers */
XLSX.utils.sheet_add_aoa(worksheet, [["Name", "Birthday"]], { origin: "A1" });
/* calculate column width */
const max_width = rows.reduce((w, r) => Math.max(w, r.name.length), 10);
worksheet["!cols"] = [ { wch: max_width } ];
/* create an XLSX file and try to save to Presidents.xlsx */
XLSX.writeFile(workbook, "Presidents.xlsx");
})();
</script>
<body>
Install the dependencies:
$ npm i --save https://cdn.sheetjs.com/xlsx-latest/xlsx-latest.tgz
Save the following script to snippet.js
and run node snippet.js
:
const XLSX = require("xlsx");
(async() => {
/* fetch JSON data and parse */
const url = "https://sheetjs.com/executive.json";
const raw_data = await (await fetch(url)).json();
/* filter for the Presidents */
const prez = raw_data.filter(row => row.terms.some(term => term.type === "prez"));
/* flatten objects */
const rows = prez.map(row => ({
name: row.name.first + " " + row.name.last,
birthday: row.bio.birthday
}));
/* generate worksheet and workbook */
const worksheet = XLSX.utils.json_to_sheet(rows);
const workbook = XLSX.utils.book_new();
XLSX.utils.book_append_sheet(workbook, worksheet, "Dates");
/* fix headers */
XLSX.utils.sheet_add_aoa(worksheet, [["Name", "Birthday"]], { origin: "A1" });
/* calculate column width */
const max_width = rows.reduce((w, r) => Math.max(w, r.name.length), 10);
worksheet["!cols"] = [ { wch: max_width } ];
/* create an XLSX file and try to save to Presidents.xlsx */
XLSX.writeFile(workbook, "Presidents.xlsx");
})();
Native fetch
support was added in NodeJS 18. For older versions of NodeJS,
the script will throw an error fetch is not defined
. A third-party library
like axios
presents a similar API for fetching data:
Example using axios (click to show)
Install the dependencies:
$ npm i --save https://cdn.sheetjs.com/xlsx-latest/xlsx-latest.tgz
The differences in the script are highlighted below.
const XLSX = require("xlsx");
const axios = require("axios");
(async() => {
/* fetch JSON data and parse */
const url = "https://sheetjs.com/executive.json";
const raw_data = (await axios(url, {responseType: "json"})).data;
/* filter for the Presidents */
const prez = raw_data.filter(row => row.terms.some(term => term.type === "prez"));
/* flatten objects */
const rows = prez.map(row => ({
name: row.name.first + " " + row.name.last,
birthday: row.bio.birthday
}));
/* generate worksheet and workbook */
const worksheet = XLSX.utils.json_to_sheet(rows);
const workbook = XLSX.utils.book_new();
XLSX.utils.book_append_sheet(workbook, worksheet, "Dates");
/* fix headers */
XLSX.utils.sheet_add_aoa(worksheet, [["Name", "Birthday"]], { origin: "A1" });
/* calculate column width */
const max_width = rows.reduce((w, r) => Math.max(w, r.name.length), 10);
worksheet["!cols"] = [ { wch: max_width } ];
/* create an XLSX file and try to save to Presidents.xlsx */
XLSX.writeFile(workbook, "Presidents.xlsx");
})();
Save the following script to snippet.ts
and run with
deno run --allow-net --allow-write snippet.ts
:
// @deno-types="https://cdn.sheetjs.com/xlsx-latest/package/types/index.d.ts"
import * as XLSX from 'https://cdn.sheetjs.com/xlsx-latest/package/xlsx.mjs';
/* fetch JSON data and parse */
const url = "https://sheetjs.com/executive.json";
const raw_data = await (await fetch(url)).json();
/* filter for the Presidents */
const prez = raw_data.filter((row: any) => row.terms.some((term: any) => term.type === "prez"));
/* flatten objects */
const rows = prez.map((row: any) => ({
name: row.name.first + " " + row.name.last,
birthday: row.bio.birthday
}));
/* generate worksheet and workbook */
const worksheet = XLSX.utils.json_to_sheet(rows);
const workbook = XLSX.utils.book_new();
XLSX.utils.book_append_sheet(workbook, worksheet, "Dates");
/* fix headers */
XLSX.utils.sheet_add_aoa(worksheet, [["Name", "Birthday"]], { origin: "A1" });
/* calculate column width */
const max_width = rows.reduce((w: number, r: any) => Math.max(w, r.name.length), 10);
worksheet["!cols"] = [ { wch: max_width } ];
/* create an XLSX file and try to save to Presidents.xlsx */
XLSX.writeFile(workbook, "Presidents.xlsx");