| 'use strict'; |
| var utils = require('./utils'); |
| var support = require('./support'); |
| // private property |
| var _keyStr = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/="; |
| |
| |
| // public method for encoding |
| exports.encode = function(input) { |
| var output = []; |
| var chr1, chr2, chr3, enc1, enc2, enc3, enc4; |
| var i = 0, len = input.length, remainingBytes = len; |
| |
| var isArray = utils.getTypeOf(input) !== "string"; |
| while (i < input.length) { |
| remainingBytes = len - i; |
| |
| if (!isArray) { |
| chr1 = input.charCodeAt(i++); |
| chr2 = i < len ? input.charCodeAt(i++) : 0; |
| chr3 = i < len ? input.charCodeAt(i++) : 0; |
| } else { |
| chr1 = input[i++]; |
| chr2 = i < len ? input[i++] : 0; |
| chr3 = i < len ? input[i++] : 0; |
| } |
| |
| enc1 = chr1 >> 2; |
| enc2 = ((chr1 & 3) << 4) | (chr2 >> 4); |
| enc3 = remainingBytes > 1 ? (((chr2 & 15) << 2) | (chr3 >> 6)) : 64; |
| enc4 = remainingBytes > 2 ? (chr3 & 63) : 64; |
| |
| output.push(_keyStr.charAt(enc1) + _keyStr.charAt(enc2) + _keyStr.charAt(enc3) + _keyStr.charAt(enc4)); |
| |
| } |
| |
| return output.join(""); |
| }; |
| |
| // public method for decoding |
| exports.decode = function(input) { |
| var chr1, chr2, chr3; |
| var enc1, enc2, enc3, enc4; |
| var i = 0, resultIndex = 0; |
| |
| var dataUrlPrefix = "data:"; |
| |
| if (input.substr(0, dataUrlPrefix.length) === dataUrlPrefix) { |
| // This is a common error: people give a data url |
| // (data:image/png;base64,iVBOR...) with a {base64: true} and |
| // wonders why things don't work. |
| // We can detect that the string input looks like a data url but we |
| // *can't* be sure it is one: removing everything up to the comma would |
| // be too dangerous. |
| throw new Error("Invalid base64 input, it looks like a data url."); |
| } |
| |
| input = input.replace(/[^A-Za-z0-9\+\/\=]/g, ""); |
| |
| var totalLength = input.length * 3 / 4; |
| if(input.charAt(input.length - 1) === _keyStr.charAt(64)) { |
| totalLength--; |
| } |
| if(input.charAt(input.length - 2) === _keyStr.charAt(64)) { |
| totalLength--; |
| } |
| if (totalLength % 1 !== 0) { |
| // totalLength is not an integer, the length does not match a valid |
| // base64 content. That can happen if: |
| // - the input is not a base64 content |
| // - the input is *almost* a base64 content, with a extra chars at the |
| // beginning or at the end |
| // - the input uses a base64 variant (base64url for example) |
| throw new Error("Invalid base64 input, bad content length."); |
| } |
| var output; |
| if (support.uint8array) { |
| output = new Uint8Array(totalLength|0); |
| } else { |
| output = new Array(totalLength|0); |
| } |
| |
| while (i < input.length) { |
| |
| enc1 = _keyStr.indexOf(input.charAt(i++)); |
| enc2 = _keyStr.indexOf(input.charAt(i++)); |
| enc3 = _keyStr.indexOf(input.charAt(i++)); |
| enc4 = _keyStr.indexOf(input.charAt(i++)); |
| |
| chr1 = (enc1 << 2) | (enc2 >> 4); |
| chr2 = ((enc2 & 15) << 4) | (enc3 >> 2); |
| chr3 = ((enc3 & 3) << 6) | enc4; |
| |
| output[resultIndex++] = chr1; |
| |
| if (enc3 !== 64) { |
| output[resultIndex++] = chr2; |
| } |
| if (enc4 !== 64) { |
| output[resultIndex++] = chr3; |
| } |
| |
| } |
| |
| return output; |
| }; |