Vue.js Image Upload

Uploading images basically is a two-step process:

1. Select a file

• Send it to a server

Select a File

Before we can upload it, we have to select a file.

To allow the user to pick a file, we have to add <input type="file"> to our component template code. We also have to listen to any changes to that file. Such a change handler will trigger whenever the user picks a new file.

Like this:

<input type="file" @change="onFileChanged">
<button @click="onUpload">Upload!</button>

We now need the two handler methods in our Vue component:

methods: {
  onFileChanged (event) {
    const file = event.target.files[0]
  },
  onUpload() {
    // upload file
  }

To upload the file, we should store it in our data property:

data() {
  return {
    selectedFile: null
  }
},
methods: {
  onFileChanged (event) {
    this.selectedFile = event.target.files[0]
  },
  onUpload() {
    // upload file, get it from this.selectedFile
  }

Send the File to a Server

With the file stored in state, we can send it to a server.

For this, you can use axios. You can either send the file as binary data or wrapped in a FormData object - depending on what your REST API expects.

Send as binary data

onUpload() {
  axios.post('my-domain.com/file-upload', this.selectedFile)
}

Send as FormData

onUpload() {
  const formData = new FormData()
  formData.append('myFile', this.selectedFile, this.selectedFile.name)
  axios.post('my-domain.com/file-upload', formData)
}

Show upload progress

In both cases, you can also output the upload progress if you want to.

uploadHandler = () => {
  ...
  axios.post('my-domain.com/file-upload', formData, {
    onUploadProgress: progressEvent => {
      console.log(progressEvent.loaded / progressEvent.total)
    }
  })
}