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authorAndré Bargull <andre.bargull@gmail.com>2019-11-12 17:02:16 +0100
committerwolfbeast <mcwerewolf@wolfbeast.com>2019-11-12 17:02:16 +0100
commit899be7cedbef6678280d56a4725f2697f808bbb5 (patch)
tree3a36479c41d486699379a5ffd420c5b236774616 /js/src/builtin/Promise.js
parentb00601953bade944cd6df9cde6fcdd1f10d76feb (diff)
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Issue #1283 - Implement Promise.prototype.finally()
This resolves #1283.
Diffstat (limited to 'js/src/builtin/Promise.js')
-rw-r--r--js/src/builtin/Promise.js69
1 files changed, 69 insertions, 0 deletions
diff --git a/js/src/builtin/Promise.js b/js/src/builtin/Promise.js
index 704cbab0b..91a1e1f56 100644
--- a/js/src/builtin/Promise.js
+++ b/js/src/builtin/Promise.js
@@ -14,3 +14,72 @@ function Promise_catch(onRejected) {
// Steps 1-2.
return callContentFunction(this.then, this, undefined, onRejected);
}
+
+// Promise.prototype.finally(onFinally)
+// See https://tc39.es/proposal-promise-finally/
+function Promise_finally(onFinally) {
+ // Step 1.
+ var promise = this;
+
+ // Step 2.
+ if (!IsObject(promise))
+ ThrowTypeError(JSMSG_INCOMPATIBLE_PROTO, "Promise", "finally", "value");
+
+ // Step 3.
+ var C = SpeciesConstructor(promise, GetBuiltinConstructor("Promise"));
+
+ // Step 4.
+ assert(IsConstructor(C), "SpeciesConstructor returns a constructor function");
+
+ // Steps 5-6.
+ var thenFinally, catchFinally;
+ if (!IsCallable(onFinally)) {
+ thenFinally = onFinally;
+ catchFinally = onFinally;
+ } else {
+ // ThenFinally Function.
+ // The parentheses prevent the inferring of a function name.
+ (thenFinally) = function(value) {
+ // Steps 1-2 (implicit).
+
+ // Step 3.
+ var result = onFinally();
+
+ // Steps 4-5 (implicit).
+
+ // Step 6.
+ var promise = PromiseResolve(C, result);
+
+ // Step 7.
+ // FIXME: spec issue - "be equivalent to a function that" is not a defined spec term.
+ // https://github.com/tc39/ecma262/issues/933
+
+ // Step 8.
+ return callContentFunction(promise.then, promise, function() { return value; });
+ };
+
+ // CatchFinally Function.
+ // The parentheses prevent the inferring of a function name.
+ (catchFinally) = function(reason) {
+ // Steps 1-2 (implicit).
+
+ // Step 3.
+ var result = onFinally();
+
+ // Steps 4-5 (implicit).
+
+ // Step 6.
+ var promise = PromiseResolve(C, result);
+
+ // Step 7.
+ // FIXME: spec issue - "be equivalent to a function that" is not a defined spec term.
+ // https://github.com/tc39/ecma262/issues/933
+
+ // Step 8.
+ return callContentFunction(promise.then, promise, function() { throw reason; });
+ };
+ }
+
+ // Step 7.
+ return callContentFunction(promise.then, promise, thenFinally, catchFinally);
+}