Question

我正在尝试在此链接中传递this上下文而没有任何'黑客' - 我只想使用apply，call或bind（描述如下）：

var ArticlesCollection = Backbone.Collection.extend({
    model: ArticleModel,
    parse : function(response) {
        var dateSinceFormatter = this.dateSinceFormatter; // right now solution

        return _.chain(response)
            .map(function(response) {

                if(!_.difference(["id", "title", "link", "source", "image"], _.keys(response)).length) {
                    return {
                        id : (!response.id ? _.uniqueId() : response.id),
                        title : response.title,
                        content : response.preamble,
                        thumbnailUrl : ((!response.image) ? '' : response.image.url),
                        linkUrl: response.link,
                        timeAgo : '',
                        categoryName: '',
                        persistentUrl: response.link,
                        commentsEnabled: false
                    };
                } else {
                    return {
                        id : response.id,
                        title : response.title,
                        content : response.preamble,
                        thumbnailUrl : response.thumbnail.url,
                        linkUrl: response.url,
                        timeAgo : dateSinceFormatter(response.published.datetime, response.published.niceformat), // I want to use this.dateSinceFormatter
                        categoryName: response.mainCategory,
                        persistentUrl: response.persistentUrl,
                        commentsEnabled: response.hasComments
                    };
                }
            })
            .value();
    }
});

任何想法？

Answer 1

在显而易见的.bind()解决方案旁边，Underscore's map（就像native one）确实为回调的this context提供了第三个参数：

response.map(function(res) { … }, this)
// or
_.map(response, function(res) { … }, this)

Answer 2

您可以将上下文作为参数传递给大多数Underscore函数。例如，您可以调用

_.chain(response)
    .map(function(response) {...}, this)
    .value()

演示http://jsfiddle.net/nikoshr/MH9Qh/1/

在方法链中传递'this'上下文（使用apply / call或bind）

2 个答案: