Knowledge about file reading

Recently, a colleague asked me if js can read local files;

I remembered the article I saw about js reading local files before, and then I wrote a demo myself.

ps: This is a bit like Java's IO stream, but there are differences.

Here are some steps I summarized:

1. Get the file object
var file=document.querySelector('input');
2. Set change Event
file.onchange=function(){
　　 3. Get file resources
　　 var list=this.files;
　　 4. Create reader
　　var reader=new FileReader() ;
5. Start reading the file
The readAsDataURL() method returns a file path
The readAsText() method returns a file content (string)
reader.readAsDataURL(list[0]);
              Get the result after the file reading is completed
                                                                                                                                                                                      are are to be obtained and the result is obtained after the file is read, reader.onload=function(){
## 　　　}
}

In the event, you can look at console.dir(this) in the background; pay attention to the two methods of reading files ①readAsDataURL() method returns a file path ②readAsText() The method returns a file content (string);

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