javascript - 读取文件时设置超时

Question

使用下面的代码，我正在读取 .csv 文件:

    var fileInput = document.getElementById("uploaded-file");
    var reader = new FileReader();
    reader.onload = function () {
        var students_data = reader.result.split(/\r?\n|\r/);
        for(var count = 1; count<students_data.length; count++){
               var str_students_information = students_data[count];
               var arr_students_information = str_students_information.split(',');
               var a_student_info = [
                   {name: 'student', value: 'add-student'},
                   {name:"id",value:arr_students_information[0]},
                   {name:"name",value:arr_students_information[1]},
                   {name:"mname",value:arr_students_information[2]},
                   {name:"sname",value:arr_students_information[3]}
               ];
              sendToDatabase(a_student_info);
        }
    };
    reader.readAsBinaryString(fileInput.files[0]);

我要实现的目标是在读取文件时每 2 秒调用方法 sendToDatabase()。另一种说法是，在读取文档的一行后调用该方法并等待 2 秒，然后再读取下一行。
借助主题setTimeout in for-loop does not print consecutive values我正在玩 setTimeout()，但总是没有我需要的东西......可能我遗漏了一些东西......

Answer 1

既然你想定期做某事，你应该使用setInterval()。不是循环，而是在回调函数中递增数组索引。

var fileInput = document.getElementById("uploaded-file");
var reader = new FileReader();
reader.onload = function() {
  var students_data = reader.result.split(/\r?\n|\r/);
  var count = 1;
  var interval = setInterval(function() {
    if (count >= students_data.length) {
      clearInterval(interval);
      return;
    }
    var str_students_information = students_data[count];
    var arr_students_information = str_students_information.split(',');
    var a_student_info = [{
       {name: 'student', value: 'add-student'},
       {name:"id",value:arr_students_information[0]},
       {name:"name",value:arr_students_information[1]},
       {name:"mname",value:arr_students_information[2]},
       {name:"sname",value:arr_students_information[3]}

    ];
    sendToDatabase(a_student_info);
    count++;
  }, 2000);
};
reader.readAsBinaryString(fileInput.files[0]);