如何将onload承诺转换为Async/Await

Question

我有以下打字稿，我想使用async/await。但我似乎无法在我的脑海中梳理出如何做到这一点。

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; 
} 

能有人告诉我这个打字稿承诺如何能转换为使用async/await

Answer 1

打字稿现在支持异步功能引擎，具有ES6发电机，例如原生支持节点v4及以上版本。异步函数以async关键字为前缀;等待暂停执行，直到完成异步函数返回许诺并解开返回的Promise中的值。 - 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); 
    }); 
} 

举例消费：

async function caller() { 
    var workbook = await this.getWorkbookFromFile2(this.getFile()); 
    // The 'workbook' variable is an IWorkBook... 
}