未捕获引用错误:未定义mahi

Question

当我试图在两个函数之间传递值时，我得到了错误消息这里有一个错误"；未捕获引用错误：mahi未定义"；我已经定义了它，并在第121行运行，但仍面临错误

function encode() {
var selectedfile = document.getElementById("cimg").files;
if (selectedfile.length > 0) {
var imageFile = selectedfile[0];
var fileReader = new FileReader();
fileReader.onload = function (fileLoadedEvent) {
var srcData = fileLoadedEvent.target.result;  
window.mahi = srcData; // here i have been defined variable as mahi
console.log(mahi)   // here is variable work                
}
fileReader.readAsDataURL(imageFile);
}
}
console.log(mahi) //here is a error "Uncaught ReferenceError: mahi is not defined" i have it defined and asigned at line no 121 stilli am facing error

Answer 1

因为在encode()外部调用console.log(mahi)时，变量尚未声明。