Node xlsx module get headers of the excel file - node.js

Question

How to get the headers of the given Excel file in node xlsx (https://www.npmjs.com/package/xlsx) module?

Answer 1

Did the following in xlsx v0.16.9
const workbookHeaders = xlsx.readFile(filePath, { sheetRows: 1 });
const columnsArray = xlsx.utils.sheet_to_json(workbookHeaders.Sheets[sheetName], { header: 1 })[0];

Answer 2

As I could find, there's no exposed method to get headers of the Excel file from the module. So I copied few functions (With all respect to author. https://github.com/SheetJS/js-xlsx) from their source code and make that work with few changes.
function getHeaders(sheet){
var header=0, offset = 1;
var hdr=[];
var o = {};
if (sheet == null || sheet["!ref"] == null) return [];
var range = o.range !== undefined ? o.range : sheet["!ref"];
var r;
if (o.header === 1) header = 1;
else if (o.header === "A") header = 2;
else if (Array.isArray(o.header)) header = 3;
switch (typeof range) {
case 'string':
r = safe_decode_range(range);
break;
case 'number':
r = safe_decode_range(sheet["!ref"]);
r.s.r = range;
break;
default:
r = range;
}
if (header > 0) offset = 0;
var rr = XLSX.utils.encode_row(r.s.r);
var cols = new Array(r.e.c - r.s.c + 1);
for (var C = r.s.c; C <= r.e.c; ++C) {
cols[C] = XLSX.utils.encode_col(C);
var val = sheet[cols[C] + rr];
switch (header) {
case 1:
hdr.push(C);
break;
case 2:
hdr.push(cols[C]);
break;
case 3:
hdr.push(o.header[C - r.s.c]);
break;
default:
if (val === undefined) continue;
hdr.push(XLSX.utils.format_cell(val));
}
}
return hdr;
}
function safe_decode_range(range) {
var o = {s:{c:0,r:0},e:{c:0,r:0}};
var idx = 0, i = 0, cc = 0;
var len = range.length;
for(idx = 0; i < len; ++i) {
if((cc=range.charCodeAt(i)-64) < 1 || cc > 26) break;
idx = 26*idx + cc;
}
o.s.c = --idx;
for(idx = 0; i < len; ++i) {
if((cc=range.charCodeAt(i)-48) < 0 || cc > 9) break;
idx = 10*idx + cc;
}
o.s.r = --idx;
if(i === len || range.charCodeAt(++i) === 58) { o.e.c=o.s.c; o.e.r=o.s.r; return o; }
for(idx = 0; i != len; ++i) {
if((cc=range.charCodeAt(i)-64) < 1 || cc > 26) break;
idx = 26*idx + cc;
}
o.e.c = --idx;
for(idx = 0; i != len; ++i) {
if((cc=range.charCodeAt(i)-48) < 0 || cc > 9) break;
idx = 10*idx + cc;
}
o.e.r = --idx;
return o;
}
Call getHeaders function by passing the Work Sheet will return the headers array of the excel sheet.

Answer 3

Have a look here:
https://www.npmjs.com/package/xlsx if we go through the documentation. It says that we need to pass options By default, sheet_to_json scans the first row and uses the values as headers. With the header: 1 option, the function exports an array of arrays of values.
So the whole code goes like this:
const data = e.target.result;
const workbook = XLSX.read(data, { type: "array" });
console.log(workbook);
const firstSheetName = workbook.SheetNames[0];
const worksheet = workbook.Sheets[firstSheetName];
const options = { header: 1 };
const sheetData2 = XLSX.utils.sheet_to_json(worksheet, options);
const header = sheetData2.shift();
console.log(header); //you should get your header right here
Where e.target comes from your input.