Delay to next function in method chain

Question

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();

I don't get why somebody voted to close. This is a very real and interesting question. — Denys Séguret, Jan 16 '13 at 18:56

Denys Séguret · Accepted Answer · 2013-01-16T18:59:33.900

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

@user1982408 I edited with a more able queue and an example of chaining with an arbitrary function. Note that this is still simplistic and doesn't aim at replacing jQuery's queue for all usages ;) — Denys Séguret, Jan 16 '13 at 18:55
boggles my mind at first but I am begnning to understand the logic - seriously thank you — user1982408, Jan 16 '13 at 18:57

score 3 · Answer 2 · answered Jan 16 '13 at 20:01

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();

Delay to next function in method chain

2 Answers2

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