functional requirement

1. Picture to base64

2.base 64 to binary array

3. Save binary data to file and download to local

resolvent

Question 1:

reference material

vue element upload picture to base64

Specific code

getBase64(file) {
      return new Promise(function (resolve, reject) {
        let reader = new FileReader();
        let imgResult = "";
        reader.readAsDataURL(file);
        reader.onload = function () {
          imgResult = reader.result;
        };
        reader.onerror = function (error) {
          reject(error);
        };
        reader.onloadend = function () {
          resolve(imgResult);
        };
      });
}
beforeUpload(file) {
    this.getBase64(file).then(res => {
        console.log(res);
   })
}

Question 2

reference material

base 64 to bytes array

Specific code

    beforeUpload(file) {
      var fileName = file.name || ''

      this.getBase64(file).then(res => {
        // console.log(res);
 
        //Binary array conversion
        var bytes = window.atob(res.split(',')[1]);        //Remove url And convert to byte

        //Handling exceptions,take ascii Convert code less than 0 to greater than 0
        var ab = new ArrayBuffer(bytes.length);
        var ia = new Uint8Array(ab);
        for (var i = 0; i < bytes.length; i++) {
          ia[i] = bytes.charCodeAt(i);
        }

        console.log("ia", ia)
      });
}

Question 3

reference material

Save the data in memory as a file and download it locally

Specific implementation

Method 2 in reference

Specific code

  function  downFile(json1) {
      var elementA = document.createElement('a');

      elementA.setAttribute('href', 'data:text/plain;charset=utf-8,' + json1);
      elementA.setAttribute('download', +new Date() + ".txt");
      elementA.style.display = 'none';
      document.body.appendChild(elementA);
      elementA.click();
      document.body.removeChild(elementA);
    },

 beforeUpload(file) {
      var fileName = file.name || ''

      this.getBase64(file).then(res => {
        // console.log(res);
        //Binary array conversion
        var bytes = window.atob(res.split(',')[1]);        //Remove url And convert to byte

        //Handling exceptions,take ascii Convert code less than 0 to greater than 0
        var ab = new ArrayBuffer(bytes.length);
        var ia = new Uint8Array(ab);
        for (var i = 0; i < bytes.length; i++) {
          ia[i] = bytes.charCodeAt(i);
        }
        this.downFile(ia)
        console.log("ia", ia)
      });
}