Function resolvePropValue

packages/runtime-core/src/componentProps.ts:452–506

(
  options: NormalizedProps,
  props: Data,
  key: string,
  value: unknown,
  instance: ComponentInternalInstance,
  isAbsent: boolean,
)

}

function resolvePropValue(
  options: NormalizedProps,
  props: Data,
  key: string,
  value: unknown,
  instance: ComponentInternalInstance,
  isAbsent: boolean,
) {
  const opt = options[key]
  if (opt != null) {
    const hasDefault = hasOwn(opt, class="st">'default')
    class="cm">// default values
    if (hasDefault && value === undefined) {
      const defaultValue = opt.default
      if (
        opt.type !== Function &&
        !opt.skipFactory &&
        isFunction(defaultValue)
      ) {
        const { propsDefaults } = instance
        if (key in propsDefaults) {
          value = propsDefaults[key]
        } else {
          const reset = setCurrentInstance(instance)
          value = propsDefaults[key] = defaultValue.call(
            __COMPAT__ &&
              isCompatEnabled(DeprecationTypes.PROPS_DEFAULT_THIS, instance)
              ? createPropsDefaultThis(instance, props, key)
              : null,
            props,
          )
          reset()
        }
      } else {
        value = defaultValue
      }
      class="cm">// #9006 reflect default value on custom element
      if (instance.ce) {
        instance.ce._setProp(key, value)
      }
    }
    class="cm">// boolean casting
    if (opt[BooleanFlags.shouldCast]) {
      if (isAbsent && !hasDefault) {
        value = false
      } else if (
        opt[BooleanFlags.shouldCastTrue] &&
        (value === class="st">'' || value === hyphenate(key))
      ) {
        value = true
      }
    }
  }
  return value
}

const mixinPropsCache = new WeakMap<ConcreteComponent, NormalizedPropsOptions>()