let main = function() {
    let last_timestamp = 0;
    let func_id;

   let step = (timestamp) => {
    console.log(timestamp - last_timestamp);
    last_timestamp = timestamp;
    $('div').width($('div').width() + 0.5);
    if(timestamp / 1000 <= 10) {
        func_id = requestAnimationFrame(step);  //递归，div标签每秒钟增加60px
    }
   }
   func_id = requestAnimationFrame(step);
   $('div').click(function() {
    cancelAnimationFrame(func_id);
   })
   $('div').click(function() {
    requestAnimationFrame(step);
   })


}
export {
    main
}