---
layout: api
id: promise.method
title: Promise.method
---
[← Back To API Reference](/docs/api-reference.html)
<div class="api-code-section"><markdown>
##Promise.method
```js
Promise.method(function(...arguments) fn) -> function
```
Returns a new function that wraps the given function `fn`. The new function will always return a promise that is fulfilled with the original functions return values or rejected with thrown exceptions from the original function.
This method is convenient when a function can sometimes return synchronously or throw synchronously.
Example without using `Promise.method`:
```js
MyClass.prototype.method = function(input) {
if (!this.isValid(input)) {
return Promise.reject(new TypeError("input is not valid"));
}
if (this.cache(input)) {
return Promise.resolve(this.someCachedValue);
}
return db.queryAsync(input).bind(this).then(function(value) {
this.someCachedValue = value;
return value;
});
};
```
Using the same function `Promise.method`, there is no need to manually wrap direct return or throw values into a promise:
```js
MyClass.prototype.method = Promise.method(function(input) {
if (!this.isValid(input)) {
throw new TypeError("input is not valid");
}
if (this.cache(input)) {
return this.someCachedValue;
}
return db.queryAsync(input).bind(this).then(function(value) {
this.someCachedValue = value;
return value;
});
});
```
</markdown></div>
<div id="disqus_thread"></div>
<script type="text/javascript">
var disqus_title = "Promise.method";
var disqus_shortname = "bluebirdjs";
var disqus_identifier = "disqus-id-promise.method";
(function() {
var dsq = document.createElement("script"); dsq.type = "text/javascript"; dsq.async = true;
dsq.src = "//" + disqus_shortname + ".disqus.com/embed.js";
(document.getElementsByTagName("head")[0] || document.getElementsByTagName("body")[0]).appendChild(dsq);
})();
</script>
<noscript>Please enable JavaScript to view the <a href="https://disqus.com/?ref_noscript" rel="nofollow">comments powered by Disqus.</a></noscript>