Angular 2 FileReader: A comprehensive guide

Question

Angular 2 FileReader: A comprehensive guide

I have a situation where I need to upload an image in section X and pass the base 64 data of the uploaded image to section Y. But I am encountering some difficulties in section X

HTML:

<input type="file" id="hotspot" (change)="uploadHotSpot($event)">

TS File:

 uploadHotSpot($event){
    var file:File = $event.target.files[0]; 
    var reader:FileReader = new FileReader();

    if (file) {
      reader.readAsDataURL(file); //reads the data as a URL
      this.pin = reader.result;
      console.log(this.pin);
    }
}

Issue: I am able to successfully see the base 64 data in the console log when uploading the image with the developer tools open. However, when I close the debugger tool and try to upload the image again, the console.log is coming out blank... Any thoughts on this?

javascript angular typescript filereader

Answer 1

Answer №1

Since that's not how it operates. It is necessary to set up an onload callback in order to receive the outcome. Here's an example:

handleUpload($event) {
    var file:File = $event.target.files[0]; 
    var reader:FileReader = new FileReader();

    reader.onload = () => {
      this.pin = reader.result;
      console.log(this.pin);
    };

    if (file) {
      reader.readAsDataURL(file); //reads the data as a URL
    }
}

Answer 2

Since that's not how it operates. It is necessary to set up an onload callback in order to receive the outcome. Here's an example:

handleUpload($event) {
    var file:File = $event.target.files[0]; 
    var reader:FileReader = new FileReader();

    reader.onload = () => {
      this.pin = reader.result;
      console.log(this.pin);
    };

    if (file) {
      reader.readAsDataURL(file); //reads the data as a URL
    }
}

Angular 2 FileReader: A comprehensive guide

Answer №1

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