historystack

Implement the javascript History interface for things other than browser history

For a command line interface (with up and down arrows for repeating commands) or an undo list, I want something that generalizes a stack, that works just like the javascript History. Unfortunately, let h = new History() is illegal. So I made my own. Same interface; push and restore anything that represents your state. The scrollRestoration property is undefined, since that’s only relevant for browser history.

Files

history.js: the code.

history.test.html: simple test suite.

Usage

See the actual History documentation for the methods and properties.

let h = new History (initialState);
h.pushState(newState);
let s = h.state; // the current state
s = h.back(); // the previous state
s = h.forward(); // return to the state of 2 lines ago.

The only difference is that the back, forward, pushState and restoreState return the current state.

There are two read-only Boolean properties that are useful and I don’t know why they aren’t included:

h.atStart === true // when at the beginning of the history list, when h.back() leaves the state unchanged
h.atEnd === true // when at the end of the history list, when h.forward() leaves the state unchanged

Note

This redefines History but that should never be a problem, since it is impossible to instantiate the original History; let h = new History() throws an Illegal Constructor error. The original window.history is unchanged.