{"id":974,"date":"2023-05-19T05:00:00","date_gmt":"2023-05-19T12:00:00","guid":{"rendered":"https:\/\/www.angulartraining.com\/daily-newsletter\/?p=974"},"modified":"2023-05-16T15:51:54","modified_gmt":"2023-05-16T22:51:54","slug":"rxjs-subscribe-callback-functions","status":"publish","type":"post","link":"https:\/\/www.angulartraining.com\/daily-newsletter\/rxjs-subscribe-callback-functions\/","title":{"rendered":"RxJs subscribe callback functions"},"content":{"rendered":"\n

At this point, it is safe to assume that most Angular developers know about the following syntax. That’s how we subscribe to an Observable to receive its data:<\/p>\n\n\n

\n
\"\"<\/figure>\n<\/div>\n\n\n

<\/p>\n\n\n\n

If you’ve been reading this newsletter for long enough, you already know that there are better ways to subscribe to Observables<\/a> and that there are no excuses for not using these techniques<\/a>.<\/p>\n\n\n\n

That said, it’s always good to know about all our available options. So here is another possible syntax:<\/p>\n\n\n

\n
\"\"<\/figure>\n<\/div>\n\n\n

<\/p>\n\n\n\n

The above syntax registers three different callback functions<\/strong>:<\/p>\n\n\n\n

    \n
  • The first one is the same as in our first example – this is where the Observable data goes.<\/li>\n\n\n\n
  • The second one is an error handler. Any exception thrown by the Observable would get caught by that callback.<\/li>\n\n\n\n
  • The third callback function is invoked when the Observable completes, which means it won’t emit any more value.<\/li>\n<\/ul>\n\n\n\n

    Note that while that syntax still works (for now), it has been deprecated in favor of a more explicit syntax, where an object is passed. Each callback is attached to a named property, making the purpose of these callbacks more obvious:<\/p>\n\n\n

    \n
    \"\"<\/figure>\n<\/div>\n\n\n

    <\/p>\n\n\n\n

    <\/p>\n","protected":false},"excerpt":{"rendered":"

    At this point, it is safe to assume that most Angular developers know about the following syntax. That’s how we subscribe to an Observable to receive its data: If you’ve been reading this newsletter for long enough, you already know that there are better ways to subscribe to Observables and that there are no excuses […]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[10],"tags":[],"class_list":["post-974","post","type-post","status-publish","format-standard","hentry","category-rxjs"],"aioseo_notices":[],"_links":{"self":[{"href":"https:\/\/www.angulartraining.com\/daily-newsletter\/wp-json\/wp\/v2\/posts\/974","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.angulartraining.com\/daily-newsletter\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.angulartraining.com\/daily-newsletter\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.angulartraining.com\/daily-newsletter\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.angulartraining.com\/daily-newsletter\/wp-json\/wp\/v2\/comments?post=974"}],"version-history":[{"count":2,"href":"https:\/\/www.angulartraining.com\/daily-newsletter\/wp-json\/wp\/v2\/posts\/974\/revisions"}],"predecessor-version":[{"id":979,"href":"https:\/\/www.angulartraining.com\/daily-newsletter\/wp-json\/wp\/v2\/posts\/974\/revisions\/979"}],"wp:attachment":[{"href":"https:\/\/www.angulartraining.com\/daily-newsletter\/wp-json\/wp\/v2\/media?parent=974"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.angulartraining.com\/daily-newsletter\/wp-json\/wp\/v2\/categories?post=974"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.angulartraining.com\/daily-newsletter\/wp-json\/wp\/v2\/tags?post=974"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}