Node.js：使用csvtojson将CSV转换为JSON后，如何在全局变量中存储jsonObj

Question

I want to store the jsonObj in a global variable. However, it doesn't work.

var jsonContent;

csvConverter.on("end_parsed", function(jsonObj){
//   console.log(jsonObj);
       jsonContent = jsonObj;
});

console.log(jsonContent);

jsonObj can be printed correctly inside {...}. But why can't I pass it to a global variable? The result of "console.log(jsonContent);" is still undefined.

undefined

Answer 1

jsonContent is global in the sense that it is available everywhere in your JS file. The problem is that csvConverter.on is asynchronous , so it will not block the program while it runs. Therefore, you will not be able to use jsonContent until after csvConverter.on runs its callback.

If you need to use jsonObj , you have to use it after your callback to csvConcerter runs. In order to do so, you can simply wrap your logic in a function and run that function once your callback is called:

var jsonContent;

csvConverter.on("end_parsed", function(jsonObj){
  jsonContent = jsonObj;
  runLogic();
});

function runLogic() {
  // this function will run after csvConverter.on callback is called
  console.log(jsonContent);
}