Javascript: Remove object from array on function call to object

Question

Not quite sure how to phrase this question (I am sure it has been asked before in some form).

My problem is essentially shown below (through some badly written pseudo-javascript code):

var list = []
for (i to somenumber)
    list.push(new myObject);

list.foreach(function(item){
    if (item.name === 'WhatIAmLookingFor')
        item.delete() <--- This needs to remove the object from list
}

So as my amazing code alludes to I want to be able to remove the item from the list by calling a function on an object in the list.

Sorry if this is an ignorant question but I cant figure out how to do this.

Try delete item instead of item.delete(). See here: stackoverflow.com/questions/208105/…. BTW just one google search was necessary — Daniel Gasser
– Daniel Gasser, Commented Sep 18, 2014 at 15:18
Not a dupe: they're asking how to remove an object with specific properties, not a given primitive. indexOf answers are useless here. — georg
– georg, Commented Sep 18, 2014 at 15:25
As georg said. Not a primitive. And I may be wrong here (new to javascript and scoping is a bit confusing to me) but the array does not exist within the scope of the item in the array. So I cant search the array from the object. — Rabid
– Rabid, Commented Sep 18, 2014 at 15:27
A function has a scope, an object not. Your items are objects. If you replace your forEach(uppercase E!)-function with georg 's filter-function, it should work. It's a clean solution you should try. You may come back and tell what went wrong. — Martin Ernst
– Martin Ernst, Commented Sep 18, 2014 at 18:10

georg · Accepted Answer · 2014-09-19 08:25:13Z

2

Instead of deleting items, use filter to keep only "good" ones.

var list = [
  { name: 'foo' },
  { name: 'bar' },  
  { name: 'removeMe' },  
  { name: 'baz' }
];

list = list.filter(function(item) {
  return item.name != 'removeMe'
});

document.write(JSON.stringify(list))

To remove an element "inside out", e.g. element.removeFrom(list), you need array.splice:

obj = function(name) {
  
  this.name = name;
  
  this.removeFrom = function(lst) {
    for (var i = 0; i < lst.length; ) {
    	if (lst[i].name == this.name)
          lst.splice(i, 1);
        else
          i++;
    }
  }
}
  
a = new obj('a');
b = new obj('b');
c = new obj('c');
x = new obj('remove');

list = [a, b, c, x, x, a, b, c, x]

x.removeFrom(list)

document.write(JSON.stringify(list))

edited Sep 19, 2014 at 8:25

answered Sep 18, 2014 at 15:23

georg

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4 Comments

Rabid Over a year ago

Can this be done from within the objects scope? I want to be calling one of the objects public methods to remove it from the list. But the array wont be within that functions scope.

georg Over a year ago

@Rabid: like someObj.removeMe(someList)?

Rabid Over a year ago

That was what I was thinking. But if I provide the array as a parameter to the function will it be passed by reference or value? Can you pass by reference in javascript?

georg Over a year ago

@Rabid: javascript is "pass by object value" - you pass a value, but this value is a pointer to an object. Therefore, you can use mutator methods, like splice, on it - see the update.

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