用于循环获取api调用并将响应存储在状态数组reactjs中

Question

getTarget(filepath){
 const filepaths = [target1, target2, target3, target4]

 for (var i =0; i< filepaths.length; i++){
   var filepath = filepaths[i]
   fetch(filepath)
      .then((response) => response.blob())
      .then(data => { 
        var reader = new FileReader();
        reader.readAsDataURL(data); 
        reader.onloadend = (event)=> {
            var base64data = reader.result;
            this.setState(prevState => ({
               targetlist: prevState.targetlist.concat(base64data)
            }))           
        }
      });
    }

目标1-4是我必须转换为base64并以有序数组形式存储在Web应用程序中的图像。我可以将4张图像存储为targetlist状态。但是，订单将全部混乱。如何确保响应返回的不同时间不会混淆列表？

或者是否有更好的方法可以获取base64字符串。图像存储在本地存储器中。

Answer 1

您可以这样使用async/await

async function getTarget(filepath) {
 const filepaths = [target1, target2, target3, target4]
 for (let i =0; i< filepaths.length; i+=1){
   const filepath = filepaths[i]
   const data = await (await fetch(filepath)).blob();
   const reader = new FileReader();
   reader.readAsDataURL(data); 
   reader.onloadend = (event) => {
        const base64data = reader.result;
        this.setState(prevState => ({
           targetlist: prevState.targetlist.concat(base64data)
        }))
   }
 }
}