How can I use forEach to set dynamic variables in JavaScript and jQuery?

Question

I am writing a jQuery plugin. There is an object of options that I want to loop through to set regular variables with. It would basically set a variable that would be the index of the object item. I want to determine if any options are left blank and if they are, set the regular variable to the default value. I would usually use the following to set options to a default if they are blank:

 var defaults = {
     someVar1 : "somevar1",
      omeVar2:  "somevar2"
 };

var someVar1;
var someVar2;

function init(options, defaults){
   if(typeof options.someVar1 === 'undefined'){
      someVar1 = defaults.someVar1;
   } else {
      someVar1 = options.someVar1;
  }
   return something();
}
function something(){
   console.log(item);
});

This can be a big pain in the butt if I have a lot of options to set. How could I modify my code below to dynamically define global variables?

function init(element, options){
    $(document).ready(function(){
         $.each(options, function(index, value){
             if(typeof options.index === 'undefined'){

              }
         });
     });
 }

just use $.extend to merge user defined options with your defaults. You normally wouldn't have $(document).ready within your plugin code — charlietfl
– charlietfl, Commented Oct 19, 2014 at 2:33
Yeah I actually do use $.extend I just didn't think it was relevant enough to include it here. — ShoeLace1291
– ShoeLace1291, Commented Oct 25, 2014 at 20:24
why do you need all these individual variables then? After you merge user opts with defaults just use if on final object properties — charlietfl
– charlietfl, Commented Oct 25, 2014 at 20:38
Doing it that way will make the code much cleaner rather than having to use an if for every action I preform. — ShoeLace1291
– ShoeLace1291, Commented Oct 25, 2014 at 20:42
whatever works for you, doesn't make much sense without seeing more of the plugin code. Normally you would be testing after the $.extend — charlietfl
– charlietfl, Commented Oct 25, 2014 at 20:52

GramThanos · Accepted Answer · 2014-10-19 02:02:35Z

1

Lets say you have an object :

var my_object = {
    item1 : 1,
    item2 : 2,
    item3 : 3,
}

var i;
for(i in my_object){
    console.log(i); 
    console.log(my_object[i]);
}
/*
    This will print in the console:
    item1
    1
    item2
    2
    item3
    3
*/

for each will not find an undefined, because undefined does not exist, unless your object is like this:

var my_object = {
    item1 : 1,
    item2 : 2,
    item3 : 3,
    item4 : undefined
}

Also :

$.each(options, function(index, value){
  // if(typeof options.index === 'undefined'){ <-- this is wrong
     if(typeof options[index]=== 'undefined'){ <-- this is correct
        // Also you have the value, why not "value === undefined" ?
     }
});

edited Oct 19, 2014 at 2:02

answered Oct 19, 2014 at 1:55

GramThanos

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4 Comments

ShoeLace1291 Over a year ago

I guess I could use the .each on my defaults object instead of options. PS: I didn't think to include that object when I posted my example :/

ShoeLace1291 Over a year ago

And so how would I use the index to define a variable?

ShoeLace1291 Over a year ago

One more thing... why is options.index wrong? Wouldn't you use that since you're working with an object?

GramThanos Over a year ago

index is a variable. When you say object.index it's like saying object['index'], the index here is not a variable its the key.

Andrew S · Accepted Answer · 2014-10-19 01:57:27Z

0

It sounds like you might want to setup a predefined variable array then based on your index of the option read its default value

var optionDefaults = ["val1", "val2", "val3"];
function init(element, options){
    $(document).ready(function(){
         $.each(options, function(index, value){
             if(typeof options.index === 'undefined'){
                  var optiondefValue = optionDefaults[index];
                  //do whatever you want here.
              }
         });
     });
 }

answered Oct 19, 2014 at 1:57

Andrew S

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