How can I convert an onload promise into Async/Await
23,715
TypeScript now supports asynchronous functions for engines that have native support for ES6 generators, e.g. Node v4 and above. Asynchronous functions are prefixed with the async keyword; await suspends the execution until an asynchronous function return promise is fulfilled and unwraps the value from the Promise returned. - Source
async function getWorkbookFromFile2(excelFile: File) {
return new Promise<xlsx.IWorkBook>((resolve, reject) => {
var reader = new FileReader();
reader.onload = (event: any) => {
var data = event.target.result;
var workbook = xlsx.read(data, { type: 'binary' });
console.log(workbook.SheetNames);
resolve(workbook);
};
reader.readAsBinaryString(excelFile);
});
}
Example consumption:
async function caller() {
var workbook = await this.getWorkbookFromFile2(this.getFile());
// The 'workbook' variable is an IWorkBook...
}
Comments
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Ali Mst almost 2 years
I have the following Typescript that I would like to use
async
/await
on. But I can't seem to sort it out in my head how to do this.private getWorkbookFromFile2(excelFile: File): Promise<xlsx.IWorkBook> { var loadedPromise = new Promise<xlsx.IWorkBook>((resolve, reject) => { var reader = new FileReader(); reader.onload = (event: any) => { var data = event.target.result; var workbook = xlsx.read(data, { type: 'binary' }); console.log(workbook.SheetNames); resolve(workbook); }; reader.readAsBinaryString(excelFile); }); return loadedPromise; }
Can someone show me how this Typescript promise can be converted to use
async
/await