在Vue.prototype._init 中有一些init函数，今天我们来研究这些init函数

Vue.prototype._init = function (options) {......{initProxy(vm);}......initLifecycle(vm);initEvents(vm);initRender(vm);callHook$1(vm, 'beforeCreate', undefined, false /* setContext */);initInjections(vm); // resolve injections before data/propsinitState(vm);initProvide(vm); // resolve provide after data/propscallHook$1(vm, 'created');......
}

上一篇中已经研究了 initState ，今天我们往下研究

initProvide(vm);

function initProvide(vm) {const provideOption = vm.$options.provide;if (provideOption) {// 获取provided的对象const provided = isFunction(provideOption)? provideOption.call(vm): provideOption;// 如过不是object对象且为null直接返回if (!isObject(provided)) {return;}// 解析provideconst source = resolveProvided(vm);// IE9 doesn't support Object.getOwnPropertyDescriptors so we have to// iterate the keys ourselves.// IE9不支持Object.getOwnPropertyDescriptors所以这里必须自己去迭代keysconst keys = hasSymbol ? Reflect.ownKeys(provided) : Object.keys(provided);for (let i = 0; i < keys.length; i++) {const key = keys[i];Object.defineProperty(source, key, Object.getOwnPropertyDescriptor(provided, key));}}
}

function resolveProvided(vm) {// by default an instance inherits its parent's provides object// but when it needs to provide values of its own, it creates its// own provides object using parent provides object as prototype.// this way in `inject` we can simply look up injections from direct// parent and let the prototype chain do the work.// 默认情况下，实例继承其父级的provides对象，// 但当它需要提供自己的值时，// 它会使用父级provides对象作为原型创建自己的provide对象。// 通过这种方式，在“inject”中，我们可以简单地从直接父级查找注入，并让原型链来完成工作。// existing 是 实例上的 _providedconst existing = vm._provided;const parentProvides = vm.$parent && vm.$parent._provided;// 如果父级上的_provided和实例上的_provided一致，就将父级上的parentProvides赋给实例上的_provided// 否则直接返回实例上的属性if (parentProvides === existing) {return (vm._provided = Object.create(parentProvides));}else {return existing;}
}