
Lesson 03 · 11 min
Lists, computed, keys
v-for without :key is a trap. Computed is a cached formula, not a method called "at every sneeze".
v-for="item in items" draws a list. Always :key="item.id". Computed: const pricey = computed(() => items.value.filter((i) => i.price > 100)). It recomputes only if its dependencies changed. A method in the template, {{ filter() }}, is called on every render — for a filter that's wasted work.
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