change event not triggered when setting an object that contains an array

Repository metrics

Stars

439 stars (439 stars)

PR merge metrics

No merged PRs in 30d (No merged PRs in 30d)

Description

var model = new Backbone.NestedModel({
    a: {
        b: [
            { c: 1 },
            { d: 2 }
        ]
    }
});

model.bind('change:a.b[0].c', function() { console.log('c changed.'); });

// The following set triggers the change event:
model.set('a.b[0].c', 3);

// The following does not trigger the change event:
model.set({
    a: {
        b: [
            { c: 4 },
            { d: 2 }
        ]
    }
});

var model2 = new Backbone.NestedModel({
    a: {
        b: { 
            c: 1
        }
    }
});

model2.bind('change:a.b.c', function() { console.log('c changed.'); });

// The following set triggers the change event:
model2.set({
    a: {
        b: {
            c: 12
        }
    }
});

Contributor guide

Research direction

Inspect the deep set logic in Backbone.NestedModel to understand why setting an object with an array does not trigger change events for nested array elements, while setting a nested object without arrays works. Compare the handling of array indices vs object keys in the change event propagation.

Tech stack

javascript

Domain

frontend

Issue type

Bug

DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.

2

Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.

1-3 hours

Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.

Active

ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.

Clear

Prerequisites

JavaScript

Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.

75