How to remove element by key from lightning map attribute

Question

I have an attribute of type map populated with some values in a component. On click action, I want to remove certain element whose key I know. I am not able to achieve this using:

var key=component.get('v.key'); delete map[key];

Error thrown is: '[TRUE is not defined] Failing descriptor'. Here 'true' is the value for 'key' in map.

I have also tried

delete map[key];

Answer 1

component is not a javascript map in way we used to thinks about javascrip maps. Let get/set methods not mislead you. The attributes of components can be set to null though. The attributes are declared in cmp file. You can declare the attribute of type Object and add/delete fields in manner you describe.

Answer 2

Correct as of Summer'17

As maps in Lightning Experience are really just objects, you can write a little helper method to remove the key.

Here is an example: (I am using a map to store errors from a number of child components)

deleteError : function(component, key) {

    // retrieve errorMap attribute
    var errorMap = component.get("v.errorMap");

    // delete the key
    delete errorMap[key];

    // set the attribute with the new errorMap
    component.set("v.errorMap", errorMap);

}

Just FYI, this is my add method:

addError : function(component, key, value) {

    // retrieve errorMap attribute
    var errorMap = component.get("v.errorMap");

    // if it is null or undefined, trying to add
    // a key generates an error, so set it as an
    // empty object.
    if (!errorMap) {
        errorMap = {};
    }

    // set the key with the value
    errorMap[key] = value;

    // set the attribute with the new errorMap
    component.set("v.errorMap", errorMap);

}

I hope this helps (please up-rate if it does ... I'm trying to build reputation ;-)

Jonathan