javascript - Google OAuth2 + Backbone + Require.js = "this"绑定(bind)问题

Question

Google OAuth2 代码基于 https://developers.google.com/api-client-library/javascript/features/authentication

LoginView 有几个函数，每个函数调用另一个函数。

当到达 checkAuth 函数时，this.handleAuthResult 返回 undefined，因为调用了 checkAuth在setTimeout内通过handleClientLoad。

如何处理this上下文问题？我可以对我的变量 - scope、clientId、apiKey 做同样的事情，而不是将它们设置为全局变量吗？

define(['underscore','jquery','backbone','text!templates/login.html','async!https://apis.google.com/js/client.js!onload'], function(_, $, Backbone, loginTpl) {
  var LoginView = Backbone.View.extend({
    template: _.template(loginTpl),

    initialize: function() {
      clientId = '';
      apiKey = '';
      scopes = 'https://www.googleapis.com/auth/plus.me';

      this.handleClientLoad();
    },

    render: function() {
      this.$el.html(this.template());
      return this;
    },

    handleClientLoad: function() {
      gapi.client.setApiKey(apiKey);
      window.setTimeout(this.checkAuth, 1);
    },

    checkAuth: function() {
      gapi.auth.authorize({ client_id: clientId, scope: scopes, immediate: true }, this.handleAuthResult);
    },

    handleAuthResult: function(authResult) {
      var authorizeButton = this.$el.find('#authorize-button');

      if (authResult && !authResult.error) {
        console.log('Authorized!');
        this.makeApiCall();
      } else {
        authorizeButton.onclick = this.handleAuthClick;
      }
    },

    handleAuthClick: function(event) {
      gapi.auth.authorize({client_id: clientId, scope: scopes, immediate: false}, this.handleAuthResult);
      return false;
    },

    makeApiCall: function() {
      gapi.client.load('plus', 'v1', function() {
        var request = gapi.client.plus.people.get({
          'userId': 'me'
        });
        request.execute(function(resp) {
          var authorizeButton = this.$el.find('#authorize-button');
          localStorage.isAuthenticated = true;
          Backbone.history.navigate('', true);
        });
      });
    }
  });

  return LoginView;
});

Answer 1

handleClientLoad 中的 setTimeout 是问题所在:

window.setTimeout(this.checkAuth, 1);

当 'window.setTimeout' 在 1ms 后执行并且不再在 LoginView 范围内执行时。

您可以使用'_.bind'将执行绑定(bind)到此。

window.setTimeout(_.bind(this.checkAuth, this), 1);

您还可以阅读'this'发帖。

希望这有帮助!