Function initComputed

docs/themes/htx/source/js/vue.js:3323–3354

(vm, computed)

  var computedWatcherOptions = { lazy: true };

  function initComputed(vm, computed) {
    // $flow-disable-line
    var watchers = (vm._computedWatchers = Object.create(null));
    // computed properties are just getters during SSR
    var isSSR = isServerRendering();

    for (var key in computed) {
      var userDef = computed[key];
      var getter = typeof userDef === "function" ? userDef : userDef.get;
      if ("development" !== "production" && getter == null) {
        warn('Getter is missing for computed property "' + key + '".', vm);
      }

      if (!isSSR) {
        // create internal watcher for the computed property.
        watchers[key] = new Watcher(vm, getter || noop, noop, computedWatcherOptions);
      }

      // component-defined computed properties are already defined on the
      // component prototype. We only need to define computed properties defined
      // at instantiation here.
      if (!(key in vm)) {
        defineComputed(vm, key, userDef);
      } else {
        if (key in vm.$data) {
          warn('The computed property "' + key + '" is already defined in data.', vm);
        } else if (vm.$options.props && key in vm.$options.props) {
          warn('The computed property "' + key + '" is already defined as a prop.', vm);
        }
      }
    }
  }

  function defineComputed(target, key, userDef) {
    var shouldCache = !isServerRendering();