105 lines
2.9 KiB
TypeScript

export interface StackItem {
name: string;
title?: string;
url: string;
}
/**
* The `History` class keeps track and manages a stack of routes that the user
* has navigated to in their session.
*
* An item can be pushed to the top of the stack using the `push` method. An
* item in the stack has a name and a URL. The name need not be unique; if it is
* the same as the item before it, that will be overwritten with the new URL. In
* this way, if a user visits a discussion, and then visits another discussion,
* popping the history stack will still take them back to the discussion list
* rather than the previous discussion.
*/
export default class History {
/**
* The stack of routes that have been navigated to.
*/
protected stack: StackItem[] = [];
/**
* Get the item on the top of the stack.
*/
getCurrent(): StackItem {
return this.stack[this.stack.length - 1];
}
/**
* Get the previous item on the stack.
*/
getPrevious(): StackItem {
return this.stack[this.stack.length - 2];
}
/**
* Push an item to the top of the stack.
*
* @param name The name of the route.
* @param title The title of the route.
* @param [url] The URL of the route. The current URL will be used if
* not provided.
*/
push(name: string, title?: string, url: string = m.route.get()) {
// If we're pushing an item with the same name as second-to-top item in the
// stack, we will assume that the user has clicked the 'back' button in
// their browser. In this case, we don't want to push a new item, so we will
// pop off the top item, and then the second-to-top item will be overwritten
// below.
const secondTop = this.stack[this.stack.length - 2];
if (secondTop && secondTop.name === name) {
this.stack.pop();
}
// If we're pushing an item with the same name as the top item in the stack,
// then we'll overwrite it with the new URL.
const top = this.getCurrent();
if (top && top.name === name) {
Object.assign(top, { url, title });
} else {
this.stack.push({ name, url, title });
}
}
/**
* Check whether or not the history stack is able to be popped.
*/
canGoBack(): boolean {
return this.stack.length > 1;
}
/**
* Go back to the previous route in the history stack.
*/
back() {
if (!this.canGoBack()) {
return this.home();
}
this.stack.pop();
m.route.set(this.getCurrent().url);
}
/**
* Get the URL of the previous page.
*/
backUrl(): string {
const secondTop = this.stack[this.stack.length - 2];
return secondTop.url;
}
/**
* Go to the first route in the history stack.
*/
home() {
this.stack.splice(0);
m.route.set('/');
}
}