The string is converted to base64

1. Use btoA functions

function encode(str){
let encode = encodeURI(str);
let base64 = btoa(encode);
return base64;
}
    encode('1234')//"MTIzNA=="
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var Base64 = { _keyStr: "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/=", // public method for encoding encode: function(input) { var output = ""; var chr1, chr2, chr3, enc1, enc2, enc3, enc4; var i = 0; input = Base64._utf8_encode(input); while (i < input.length) { chr1 = input.charCodeAt(i++); chr2 = input.charCodeAt(i++); chr3 = input.charCodeAt(i++); enc1 = chr1 >> 2; enc2 = ((chr1 & 3) << 4) | (chr2 >> 4); enc3 = ((chr2 & 15) << 2) | (chr3 >> 6); enc4 = chr3 & 63; if (isNaN(chr2)) { enc3 = enc4 = 64; } else if (isNaN(chr3)) { enc4 = 64; } output = output + this._keyStr.charAt(enc1) + this._keyStr.charAt(enc2) + this._keyStr.charAt(enc3) + this._keyStr.charAt(enc4); } return output; }, decode: function(input) { var output = ""; var chr1, chr2, chr3; var enc1, enc2, enc3, enc4; var i = 0; input = input.replace(/[^A-Za-z0-9\+\/\=]/g, ""); while (i < input.length) { enc1 = this._keyStr.indexOf(input.charAt(i++)); enc2 = this._keyStr.indexOf(input.charAt(i++)); enc3 = this._keyStr.indexOf(input.charAt(i++)); enc4 = this._keyStr.indexOf(input.charAt(i++)); chr1 = (enc1 << 2) | (enc2 >> 4); chr2 = ((enc2 & 15) << 4) | (enc3 >> 2); chr3 = ((enc3 & 3) << 6) | enc4; output = output + String.fromCharCode(chr1); if (enc3 ! = 64) { output = output + String.fromCharCode(chr2); } if (enc4 ! = 64) { output = output + String.fromCharCode(chr3); } } output = Base64._utf8_decode(output); return output; }, _utf8_encode: function(string) { string = string.replace(/\r\n/g, "\n"); var utftext = ""; for (var n = 0; n < string.length; n++) { var c = string.charCodeAt(n); if (c < 128) { utftext += String.fromCharCode(c); } else if ((c > 127) && (c < 2048)) { utftext += String.fromCharCode((c >> 6) | 192); utftext += String.fromCharCode((c & 63) | 128); } else { utftext += String.fromCharCode((c >> 12) | 224); utftext += String.fromCharCode(((c >> 6) & 63) | 128); utftext += String.fromCharCode((c & 63) | 128); } } return utftext; }, _utf8_decode: function(utftext) { var string = ""; var i = 0; var c = c1 = c2 = 0; while (i < utftext.length) { c = utftext.charCodeAt(i); if (c < 128) { string += String.fromCharCode(c); i++; } else if ((c > 191) && (c < 224)) { c2 = utftext.charCodeAt(i + 1); string += String.fromCharCode(((c & 31) << 6) | (c2 & 63)); i += 2; } else { c2 = utftext.charCodeAt(i + 1); c3 = utftext.charCodeAt(i + 2); string += String.fromCharCode(((c & 15) << 12) | ((c2 & 63) << 6) | (c3 & 63)); i += 3; } } return string; }}Copy the code

The image is converted to base64

To convert image data to Base64, first obtain the binary data of the image:

function getCanvas(w, h) {
  var c = document.createElement('canvas');
  c.width = w;
  c.height = h;
  return c;
}
  
function getPixels(img) {
  var c = getCanvas(img.width, img.height);
  var ctx = c.getContext('2d');
  ctx.drawImage(img, 0, 0);
  return ctx.getImageData(0, 0, c.width, c.height);
}


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Generate pixel matrix according to pixel information; Create image object ImageData based on pixel matrix, width and height; Use putImageData to draw out the image.

function img2Base64(img) {
  var imgData = getPixels(img).data;
  var imgWidth = getPixels(img).width;
  var imgHeight = getPixels(img).height;
  var bin = "";
  for (var i = 0; i &lt; imgData.length; i++) {
    bin += base.numToString(imgData[i]);
  }
  bin = bin + base.stringToBin("$$" + imgWidth + "," + imgHeight + "$$");
  return base.binToBase64(bin);
}
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