Function initData

static/vuejs/vue.esm.js:2719–2749

(vm)

}

function initData (vm) {
  var data = vm.$options.data;
  data = vm._data = typeof data === 'function'
    ? getData(data, vm)
    : data || {};
  if (!isPlainObject(data)) {
    data = {};
    process.env.NODE_ENV !== 'production' && warn(
      'data functions should return an object:\n' +
      'https://vuejs.org/v2/guide/components.html#data-Must-Be-a-Function',
      vm
    );
  }
  // proxy data on instance
  var keys = Object.keys(data);
  var props = vm.$options.props;
  var i = keys.length;
  while (i--) {
    if (props && hasOwn(props, keys[i])) {
      process.env.NODE_ENV !== 'production' && warn(
        "The data property \"" + (keys[i]) + "\" is already declared as a prop. " +
        "Use prop default value instead.",
        vm
      );
    } else if (!isReserved(keys[i])) {
      proxy(vm, "_data", keys[i]);
    }
  }
  // observe data
  observe(data, true /* asRootData */);
}

function getData (data, vm) {
  try {