首次加载(初始化-合并配置)

前言

mergeOptions主要是将内部默认参数与用户的options进行合并操作

1.mergeOptions

export function mergeOptions(parent, child, vm) {
  if (typeof child === "function") {
    child = child.options
  }
  normalizeProps(child, vm)
  normalizeInject(child, vm)
  normalizeDirectives(child)
  const extendsFrom = child.extends
  if (extendsFrom) {
    parent = mergeOptions(parent, extendsFrom, vm)
  }
  if (child.mixins) {
    for (let i = 0, l = child.mixins.length; i < l; i++) {
      parent = mergeOptions(parent, child.mixins[i], vm)
    }
  }
  const options = {}
  let key
  for (key in parent) {
    mergeField(key)
  }
  for (key in child) {
    if (!hasOwn(parent, key)) {
      mergeField(key)
    }
  }
  function mergeField(key) {
    const strat = strats[key] || defaultStrat
    options[key] = strat(parent[key], child[key], vm, key)
  }
  return options
}

2.normalizeProps

3.normalizeInject

4.normalizeDirectives

5.mergeField