node验证码实现

node验证码实现

csser 使用的最简单的验证码，用的 node-canvas 模块

var Canvas = require('canvas');

module.exports = function (req, res) {
    var canvas = new Canvas(100, 30),
        ctx = canvas.getContext('2d'),
        items = 'abcdefghjkmnpqrstuvwxyzABCDEFGHJKLMNPRSTUVWXYZ23456789'.split(''),
        vcode = '',
        textColors = ['#FD0', '#6c0', '#09F', '#f30', '#aaa', '#3cc', '#cc0', '#A020F0', '#FFA500', '#A52A2A', '#8B6914', '#FFC0CB', '#90EE90'];

    ctx.fillStyle = '#000';
    ctx.fillRect(0, 0, 100, 30);
    ctx.font = 'bold 30px sans-serif';

    ctx.globalAlpha = .8;
    for (var i = 0; i < 4; i++) {
        var rnd = Math.random();
        var item = Math.round(rnd * (items.length - 1));
        var color = Math.round(rnd * (textColors.length - 1));
        ctx.fillStyle = textColors[color];
        ctx.fillText(items[item], 5 + i*23, 25);
        vcode += items[item];
    }
    
    req.session.verifycode = vcode.toLowerCase();

    canvas.toBuffer(function(err, buf){
        res.writeHead(200, { 'Content-Type': 'image/png', 'Content-Length': buf.length });
        res.end(buf);
    });
};