Question

我想知道是否有一些巧妙的方法来了解是否在当前节拍（声明函数的节拍）或Node.js事件的下一个节拍（或某个未来节拍）中调用了一个函数环

例如：

function foo(cb){

  // we can fire callback synchronously
  cb();

  // or we can fire callback asynchronously
  process.nextTick(cb);

}

说会像这样打电话给foo：

function outer(){

   const currentTickId = process.currentTickId;

  function bar(){          //bar gets created everytime outer is called..

    if(process.currentTickId === currentTickId){
       //do something
    }
    else{

     // do something else
    }


  }

  // foo is always called in the same tick that bar was
  // declared, but bar might not be called until the next tick

  foo(bar);  


}

大多数应用程序都不需要这样的东西，但是我正在编写一个库，如果有可能的话，拥有这个功能会很有用！请注意process.currentTickId由我为此示例构成

Answer 1

看起来您已经发现了process.nextTick。

您可以使用它来设置系统以实现“process.currentTickId”，因为您问题中的代码表明您需要：

process.currentTickId = 0;

const onTick = () => {
    process.currentTickId++;
    process.nextTick(onTick);
};

process.nextTick(onTick);

Answer 2

NPM 库： https://www.npmjs.com/package/event-loop-ticks

基于@Emmett 帖子的改进答案：

let _tick = 0;
const onTick = () => {
  _tick++;
  setImmediate(() => process.nextTick(onTick)).unref();
};
process.nextTick(onTick);

JavaScript / Node.js事件循环tick ids

2 个答案: