Non-standard
This feature is not on a current W3C standards track, but it is supported on the Firefox OS platform. Although implementations may change in the future and it is not supported widely across browsers, it is suitable for use in code dedicated to Firefox OS apps.
This API is available on Firefox OS for privileged or certified applications only.
The getCanGoBack() method of the HTMLIFrameElement interface is used to indicate whether it's possible to go back in the navigation history of the browser <iframe>.
Syntax
There is a DOMRequest version and a Promise version:
var instanceOfDOMRequest = instanceOfHTMLIframeElement.getCanGoBack();
instanceOfHTMLIframeElement.getCanGoBack().then(function(result) { ... });
Returns
Returns either
- A
DOMRequestobject to handle the request's success or error. If the request is successful, the request'sresultwill be a boolean indicating if the history can be navigated backward (true) or not (false). - A
Promisethat resolves with a boolean that equalstrueif the history can be navigated backward orfalseif not.
Parameters
None.
Example
function canMoveBwd() {
var request = browser.getCanGoBack();
request.onsuccess = function() {
if (request.result) {
back.disabled = false;
console.log("It's possible to navigate
the history backward.");
} else {
back.disabled = true;
console.log("It's not possible to navigate
the history backward.");
}
}
}
function canMoveBwd() {
browser.getCanGoBack().then(function(result) {
if (result) {
back.disabled = false;
console.log("It's possible to navigate
the history backward.");
} else {
back.disabled = true;
console.log("It's not possible to navigate
the history backward.");
}
});
}Specification
Not part of any specification.
Browser compatibility
| Feature | Chrome | Firefox (Gecko) | Internet Explorer | Opera | Safari (WebKit) |
|---|---|---|---|---|---|
| Basic support | Not supported | Not supported | Not supported | Not supported | Not supported |
| Feature | Android | Firefox Mobile (Gecko) | Firefox OS (Gecko) | IE Phone | Opera Mobile | Safari Mobile |
|---|---|---|---|---|---|---|
| Basic support | Not supported | Not supported | 1.0.1 | Not supported | Not supported | Not supported |
Note: Use of the Browser API requires a privileged app, and browser and/or embed-apps permissions, depending on what you want to do. See Using the Browser API for more details.