CODEWITHSUNDEEP
javascriptarrays
J Castillo
J Castillo

Reputation: 3357

map items of array to another array

I have an array:

arr = [ 1, 2 , 3 ]

And another array where i hold DOM elements as

Elem = [ 1, 3]

I need to iterate over arr and only do stuff if the index match. For example since I have elem 1 and 3 when I loop through arr something should only happen for 1 and 3 and 2 should be skipped since there is no elem 2.

Someone told me to look into associative arrays and I wonder how I can do this with the least number of lines.

I want the code to be simple and readable and so far all the examples of associative arrays make no sense and are bloated.

Upvotes: 0

Views: 84

Answers (3)

Bruno
Bruno

Reputation: 5822

Not really sure how you identify the elements in the second array but this is my suggestion. Array with ids

var arr = [ "id_1", "id_2", "id_3" ]

var Elem = {
    "id_1": html_element,
    "id_2": html_element,
    "id_3": html_element
}

Then all you need to do is

for( var i = 0; i < arr.length; i++ ) {
    if( Elem[ arr[i] ] ) {
        // do stuff
    }
}

Upvotes: 1

Mike Grabowski
Mike Grabowski

Reputation: 1965

I modified the second array a bit to allow defining multiple actions in one place. I am not sure if I understand you correctly.

// array of DOM objects available
var arr = ['object1-selector', 'object2-selector', 'object3-selector'];

// array of actions with items that the method should be applied to
var actions = [
    {
       items: ['object1-selector', 'object3-selector'],
       perform: function(elem) {
          alert(elem);
       }
    },
    {
       items: ['object2-selector'],
       perform: function(elem) {
          alert(elem);
       }
    },
    {
       items: ['object4-selector'],
       perform: function(elem) {
          alert(elem);
       }
    }
];

//forEach loop that iterates over actions and checks if selector exists. 
//If yes - it invokes the method
actions.forEach(function(action) {
    action.items.forEach(function(item) {
        if(arr.indexOf(item) > -1) {
              action.perform(item);
        }
    });
});

If you want to have actions defined in one place and objects in a multidimensional array - let me know. I will try to adjust the example. If you don't store selectors but whole DOM objects, just modify the items: array and loop, that checks if element exists.

Oh, and here is jsfiddle: http://jsfiddle.net/3WJxc/2/. jQuery used only for alert() to show you working example.

Upvotes: 1

nicael
nicael

Reputation: 19024

for(var i = 0;i<arr.length;i++){
if(Elem.indexOf(arr[i])>-1){
//Elem contains arr[i] (contains object that at index i in arr)
//will be called only for 1 and 3 in arr
arr[i] = ... //do what you want with this object.
}
}

Do you mean this?

Upvotes: 1

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