js 高级函数

function animation(duration,from,to,handler){const dis=to-from;const speed=dis/duration;const startTime=Date.now();let value=from;handler(value);function _run(){const now=Date.now();const time=now-startTime;if(time>=duration){value=to;return }const d=time*speed;value=from+d;handler(value);requestAnimationFrame(_run);}requestAnimationFrame(_run);
}function debounce(fun,delay){let timerId=null;return function(...args){timerId && clearTimeout(timerId);timerId=setTimeout(()=>{fun.apply(this,args)},delay)}
}function paralleltask(tasks,parallelCount){return new Promise(resolve=>{if(tasks.length===0){resolve();return;}let nextIndex=0;let taskFinish=0;function _run(){const task=tasks[nextIndex];nextIndex++;task().then(()=>{taskFinish++;if(nextIndex<tasks.length){_run();}else{if(taskFinish===tasks.length){resolve();}}})}for(let i=0;i<parallelCount && i<tasks.length;i++){_run();}})}function groupby(arr,generatekey){const newObj={};for(let item of arr){const key=generatekey(item);if(!newObj[key]){newObj[key]=[]}newObj[key].push(item)}return newObj
}function parallelRendertask(taskdatas,renderTask){if(taskdatas.length===0){return;}let i=0;function _run(){if(i===taskdatas.length){return;}requestIdleCallback(idle=>{while(idle.timeRemaining()>0 && i<taskdatas.length){//做相应的渲染任务
                renderTask(taskdatas[i]);i++;}_run;})       }_run();
}