Delay to next function in method chain

问题

I am trying to learn more about Method chaining in Javascript and would like to know the proper way to create a delay with no jQuery to the next function in the chain:

var foo = function() {
    this.delay = function(per) {
        setTimeout(start, per);
        return this;
    };
    this.start = function() {
        alert('start!');
    };
};

var bar = new foo().delay(1000).start();

回答1:

This isn't easy to do. jQuery uses a specific queue system.

Suppose you want to do it without jQuery, you would have to implement a queue yourself.

For example this very simplistic implementation :

var foo = function() {
    var queue = [];
    var timer;
    this.delay = function(per) {
      timer = setTimeout(function(){
        timer = 0;
        var f;
        while (f = queue.shift()) f();
      }, per);
      return this;
    };
    this.addFunction = function(f) {
      if (timer) queue.push(f);
      else f();
      return this;
    };
    this.start = function() {
       this.addFunction(function(){alert('start')});
       return this;
    };
};

Demonstration

If you want to chain another function not defined in foo, you may do

var bar = new foo().delay(3000).start()
    .addFunction(function(){alert("another chained one")});

Demonstration

回答2:

This will allow you to chain with multiple delays: http://jsfiddle.net/z4Uyf/1/

js:

var foo = function() {

  var delayed = [];
  var delayExecution = false;
  var delayCount = 0;   
  function handleDelay(func){
    delayed.push(func);
    delayCount++;
  }

   function delayDone(){
     delayExecution = false;
     if( typeof(delayed[0]) == "function" ){
       delayed[0]();
       delayed.splice(0,1);
     }
     if( delayed.length > 0 ) delayExecution = true;
   }

   this.delay = function(per) {
        delayExecution = true;
        setTimeout(function(){
          delayDone();
        }, per);
        return this;
   };

  this.start = function() {
    if( delayExecution ){
     handleDelay(arguments.callee);
    }else{
     alert("start!");
    }
    return this;
  };
};

var bar = new foo().delay(1000).start().delay(5000).start();

来源：https://stackoverflow.com/questions/14365318/delay-to-next-function-in-method-chain

标签

javascript

delay

method-chaining