nodejs base 64符号化復号

var b = new Buffer('JavaScript');

var s = b.toString('base64');

// SmF2YVNjcmlwdA==





var b = new Buffer('SmF2YVNjcmlwdA==', 'base64')

var s = b.toString();

// JavaScript

var b = new Buffer('SmF2YVNjcmlwdA==', 'base64')

var s = b.toString('hex');

// 4a617661536372697074





var b = new Buffer('4a617661536372697074', 'hex')

var s = b.toString('utf8');

// JavaScript

var fs = require('fs');



// function to encode file data to base64 encoded string

function base64_encode(file) {

    // read binary data

    var bitmap = fs.readFileSync(file);

    // convert binary data to base64 encoded string

    return new Buffer(bitmap).toString('base64');

}



// function to create file from base64 encoded string

function base64_decode(base64str, file) {

    // create buffer object from base64 encoded string, it is important to tell the constructor that the string is base64 encoded

    var bitmap = new Buffer(base64str, 'base64');

    // write buffer to file

    fs.writeFileSync(file, bitmap);

    console.log('******** File created from base64 encoded string ********');

}



// convert image to base64 encoded string

var base64str = base64_encode('kitten.jpg');

console.log(base64str);

// convert base64 string back to image 

base64_decode(base64str, 'copy.jpg');