Node xlsx module get headers of the excel file

Question

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

Answer 1

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.