问将数组项映射到另一个数组

EN

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.
}
}

// 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);
        }
    });
});

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

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

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