JavaScript – How to Remove Property by Value from Object

javascript

I have a simple object like this:

var obj = {
    "option1": "item1",
    "option2": "item2",
    "option3": "item3"
};

For adding a new property to the object I'm using the following code:

obj[this.value] = this.innerHTML;

// this.innerHTML is used just because I'm adding the value I get from a DOM element

Is there a function that can help me remove a property from the object, that receives as a parameter the value of the key-value pair?

For example removeItem('item3');.

Best Answer

That would probably be delete :

delete obj['option1'];

FIDDLE

To do it by value, you'd do something like :

function deleteByVal(val) {
    for (var key in obj) {
        if (obj[key] == val) delete obj[key];
    }
}

deleteByVal('item1');

FIDDLE

Related Solutions

JavaScript – How to Remove a Property from an Object

Using delete:

delete selectedMap[event.target.id];

You're setting the value incorrectly, though. Here's the correct way:

if(event.target == true){
    var key = event.target.id;   // <== No quotes
    var val = event.target.name; // <== Here either
    selectedMap[key] = val;
}

In fact, you could:

if(event.target == true){
    selectedMap[event.target.id] = event.target.name;
}

Getting the event target stuff out of the way, it's easier to envision this with simple strings:

var obj = {};
obj.foo = "value of foo";
alert(obj.foo);    // alerts "value of foo" without the quotes
alert(obj["foo"]); // ALSO alerts "value of foo" without the quotes, dotted notation with a literal and bracketed notation with a string are equivalent
delete obj.foo;    // Deletes the `foo` property from the object entirely
delete obj["foo"]; // Also deletes the `foo` property from the object entirely
var x = "foo";
delete obj[x];     // ALSO deeltes the `foo` property

When using a plain object like this, I always use a prefix on my keys to avoid issues. (For instance, what would happen if your target element's ID was "toString"? The object already has an [inherited] property called "toString" and things would get Very Weird Very Quickly.)

So for me, I do this:

if(event.target == true){
    selectedMap["prefix" + event.target.id] = event.target.name;
}

...and of course:

delete selectedMap["prefix" + event.target.id];

Best Answer

Related Solutions

JavaScript – How to Remove a Property from an Object

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