Vue.js Debugging Guide

A systematic approach to debugging Vue.js 3 applications, covering common error patterns, debugging tools, and resolution strategies.

Common Error Patterns

1. Reactivity Not Working

Symptoms:

• Data changes but UI does not update
• Computed properties return stale values
• Watch callbacks not firing

Common Causes:

// WRONG: Adding new properties to reactive object
const state = reactive({ count: 0 })
state.newProp = 'value'  // Not reactive in Vue 2, works in Vue 3 with Proxy