Error Handling
A single .fail() at the end of a chain catches any rejection. Use .then(success, failure) to handle errors at each step individually.
jQuery
Intermediate
4 min read
Error Handling in Deferred Chains
Example
$.getJSON("/api/step1")
.then(function(data) {
if (!data.ok) return $.Deferred().reject("Step 1 failed");
return $.getJSON("/api/step2?id=" + data.id);
})
.then(function(result) {
render(result);
})
.fail(function(err) {
showError("Operation failed: " + err);
}); Pro Tip
Returning a rejected Deferred from .then() propagates the failure to the .fail() handler.