Question

我有一个函数，它传递了一个带有数据uri的对象。 uri将转换为blob并使用createObjectURL显示。如何确保正确发布？

目前，如果我在chrome / firefox中拍摄快照，看起来它没有被正确释放，因为即使在我关闭对话框之后内存仍然被分配。

这是我尝试过的：

  import swal from 'sweetalert2';

  function dataURItoBlob (dataURI) {
    // convert base64 to raw binary data held in a string
    // doesn't handle URLEncoded DataURIs - see SO answer #6850276 for code that does this
    var byteString = atob(dataURI.split(',')[1]);

    // separate out the mime component
    var mimeString = dataURI.split(',')[0].split(':')[1].split(';')[0];

    // write the bytes of the string to an ArrayBuffer
    var ab = new ArrayBuffer(byteString.length);

    // create a view into the buffer
    var ia = new Uint8Array(ab);

    // set the bytes of the buffer to the correct values
    for (var i = 0; i < byteString.length; i++) {
      ia[i] = byteString.charCodeAt(i);
    }

    // write the ArrayBuffer to a blob, and you're done
    var blob = new Blob([ab], {type: mimeString});
    return blob;
  }

  /**
   * Shows an attachment in the browser
   * @param {Object} result The result object
   * @param {String} result.uri The data uri string
   */
  export function showAttachment (result) {
    // It is necessary to create a new blob object with mime-type explicitly set
    // otherwise only Chrome works like it should
    var newBlob = dataURItoBlob(result.uri);

    // get a url
    const url = URL.createObjectURL(newBlob);

    const linkContent = newBlob.type.indexOf('image') > -1
      ? `<img src="${url}" alt="" style="width:100%;" />` : result.id;
    const html = `<a href="${url}" target="_blank"><i class="fa fa-download"></i> ${linkContent}</a>`;

    swal({
      title: 'File Download',
      html: html,
      confirmButtonText: '<i class="fa fa-check"></i> Done!'
    }).then(() => {
      window.URL.revokeObjectURL(url);
    });
  }

Answer 1

大多数人在分析内存时忘记的是，在释放资源后，GC并不总是直接启动。特别是V8通常是罕见的停止世界。要真正测试它是否被收集，请调用它几千次，以便RAM填满并且GC需要启动。

如何在Javascript中正确释放blob分配的内存？

1 个答案: