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Updated on 2025-04-14

Implement pause to restore downloads when downloading

Implement pause to restore downloads when downloading

Updated: January 31, 2025 09:58:57 Author: LCG Yuan
This article mainly introduces the implementation of pause and recovery of downloads when downloading, and controls the download process by using XMLHttpRequest object. The article introduces the example code in detail. Friends who need it, please learn with the editor below.

Implementing the pause and recovery function during download in Vue, usually with the help ofXMLHttpRequestObjects to control the download process.XMLHttpRequestAllows pause and continue requests during downloading.

Implementation steps

  • Create Vue Components: Create a Vue component that contains download, pause, and restore buttons.
  • InitializationXMLHttpRequestObject: Initialize a componentXMLHttpRequestObject, used to process download requests.
  • Implement download function:passXMLHttpRequestStart a download request and listen to the download progress.
  • Implement pause function:pauseXMLHttpRequestask.
  • Implement recovery function:recoverXMLHttpRequestask.

Detailed code

<template>
  <div>
    <!-- Download button，Click to trigger downloadFile method -->
    <button @click="downloadFile">download</button>
    <!-- Pause button，Click to trigger pauseDownload method -->
    <button @click="pauseDownload" :disabled="!isDownloading || isPaused">pause</button>
    <!-- Recovery button，Click to trigger resumeDownload method -->
    <button @click="resumeDownload" :disabled="!isPaused">recover</button>
    <!-- 显示download进度 -->
    <p>download进度: {{ progress }}%</p>
  </div>
</template>

<script>
export default {
  data() {
    return {
      xhr: null, //Storing XMLHttpRequest object      isDownloading: false, // Tags whether it is downloading      isPaused: false, // Tag whether to pause download      progress: 0, // Download progress percentage      url: '/', // The URL of the download file needs to be replaced with the actual file URL      resumeOffset: 0 // Restore the offset when downloading    };
  },
  methods: {
    downloadFile() {
      // Create a new XMLHttpRequest object       = new XMLHttpRequest();
      // Open a GET request and set the response type to blob      ('GET', , true);
       = 'blob';

      // If there is a recovery offset, set the Range of the request header      if ( > 0) {
        ('Range', `bytes=${}-`);
      }

      // Listen to download progress events      ('progress', (event) => {
        if () {
          // Calculate the download progress percentage           = (( + ) / ( + ) * 100);
        }
      });

      // Listen to request completion event      ('load', () => {
         = false;
         = false;
         = 0;
        // Create a temporary URL object        const url = ();
        // Create a <a> element        const a = ('a');
         = url;
         = ''; // Set the download file name        // Simulate click on the <a> element to download        ();
        // Release temporary URL object        (url);
      });

      // Listen to request error events      ('error', () =&gt; {
         = false;
         = false;
        ('The download error');
      });

      // Start sending request      ();
       = true;
       = false;
    },
    pauseDownload() {
      if ( &amp;&amp;!) {
        // Pause download and terminate XMLHttpRequest request        ();
         = true;
        // Record the current download offset         +=  || 0;
      }
    },
    resumeDownload() {
      if () {
        // Resume download and call the downloadFile method        ();
      }
    }
  }
};
&lt;/script&gt;

Code Comments

The comments in the code have explained the role of each step in detail, and here are some key parts summary:

  • downloadFileMethod: CreateXMLHttpRequestObject, initiate download request, listen for download progress and completion events, and process the file saved after download is completed.
  • pauseDownloadMethod: Pause download and terminateXMLHttpRequestRequest and record the current download offset.
  • resumeDownloadMethod: Recover download, calldownloadFileMethod and set the request headerRangeContinue downloading from the specified location.

Instructions for use

  • Replace file URL:WilldataInurlReplace the attribute with the URL of the file that is actually downloaded.
  • Introducing components: Save the above code as a Vue component (for example), and then introduce the component where you need to use it.
<template>
  <div>
    <DownloadComponent />
  </div>
</template>

<script>
import DownloadComponent from './';

export default {
  components: {
    DownloadComponent
  }
};
</script>
  • Run the project: Run the Vue project in the browser, click the "Download" button to start downloading the file, click the "Pause" button to pause the download, and click the "Recover" button to continue downloading.

This is the article about pausing the download when downloading. For more related content, please search for my previous article or continue browsing the related articles below. I hope everyone will support me in the future!

  • download
  • pause
  • recover

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