4 examples of 'read excel file in js' in JavaScript

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readSheet(sheet){
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    let excel = this.readFile();
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    if(typeof sheet === 'number'){
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        return XLSX.utils.sheet_to_json(excel.Sheets[excel.SheetNames[sheet]]);
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    } else if(typeof sheet === 'string'){
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        return XLSX.utils.sheet_to_json(excel.Sheets[sheet]);
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    } else {
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        return null;
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    }
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}

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readSheet(x) {
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  return fs.readFileSync(join(__dirname, './style', x), 'utf8');
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}

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function excel2json(files: File[], cb: CallBack, defval = ''): any {
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    // https://caniuse.com/#search=FileReader
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    let reader = new FileReader();
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    if (!files || files.length === 0) {
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        return;
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    }
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    let file = files[0];
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    reader.onerror = (err: any) => {
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        console.error('File read error: ', err);
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    };
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    reader.onload = (e: any) => {
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        // pre-process data
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        let binary = '';
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        let bytes = new Uint8Array(e.target.result);
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        let length = bytes.byteLength;
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        for (let i = 0; i < length; i++) {
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            binary += String.fromCharCode(bytes[i]);
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        }
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        // read workbook
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        let wb = XLSX.read(binary, {type: 'binary'});
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        let res = {};
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        for (let name of wb.SheetNames) {
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            let ws = wb.Sheets[name];
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            res[name] = XLSX.utils.sheet_to_json(ws, {defval});
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        }
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        if (typeof cb === 'function') {
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            cb(res);
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        }
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    };
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    reader.readAsArrayBuffer(file);
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}

8
export function readFirstSheet(data: any, options: XLSX.ParsingOptions): any[][] {
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  const wb: XLSX.WorkBook = read(data, options);
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  const ws: XLSX.WorkSheet = wb.Sheets[wb.SheetNames[0]];
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  return sheet_to_json(ws, { header: 1, raw: true });
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}