jTimer

很多时候我们需要按时间间隔执行一个任务,当满足一定条件时停止执行.此插件旨在解决这一经常遇到的问题.

jTimer:

(function ($) {
    $.extend({
        timer: function (action,context,time) {
            var _timer;
            if ($.isFunction(action)) {
                (function () {
                    _timer = setInterval(function () {
                        if (!action(context)) {
                            clearInterval(_timer);
                        }
                    }, time);
                })();
            }
        }
    });
})(jQuery);

demo:

<!DOCTYPE html>
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
    <meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
    <title>画布</title>
    <script src="../script/jquery.min.js"></script>
    <script src="../script/jTimer.js"></script>
    <style type="text/css">
        #wrap
        {
            display: table;
            margin: 0 auto;
        }

        #cvs
        {
            display: table-cell;
            vertical-align: middle;
        }
    </style>
    <script type="text/javascript">
        function drawRound(context) {            
            if (context.counterclockwise) {
                draw(context.x, context.y, context.r, context.start, context.start - Math.PI / 50, context.counterclockwise);
                context.start -= Math.PI / 50;
                return context.start > 0.5 * Math.PI;
            }
            else {
                draw(context.x, context.y, context.r, context.start, context.start + Math.PI / 50, context.counterclockwise);
                context.start += Math.PI / 50;
                return context.start < Math.PI;
            }
        }
        function draw(x, y, r, sAngle, eAngle, counterclockwise) {
            var cvs = document.getElementById("cvs");
            ctx = cvs.getContext("2d");
            ctx.strokeStyle = "#f00";
            ctx.beginPath();
            ctx.arc(x, y, r, sAngle, eAngle, counterclockwise);
            ctx.stroke();
        }
        $(function () {
            $.timer(drawRound, { x: 100, y: 100, r: 50, start: 1.5 * Math.PI, counterclockwise: true }, 200);
            $.timer(drawRound, { x: 100, y: 100, r: 60, start: 0, counterclockwise: false }, 200);
        });
    </script>
</head>
<body>
    <div id="wrap">
        <canvas id="cvs" height="400" width="500"></canvas>
    </div>
</body>
</html>