Store turbolinks cache in window.localStorage

turbolinks_local_storage.js

// NB: This is a proof of concept and needs work before using in production.
// https://github.com/turbolinks/turbolinks/issues/196#issuecomment-320610483

// Copy paste the javascript below to somewhere that loads after turbolinks.js.

// Source: Converted coffee to JS with: https://awsm-tools.com/code/coffee2js
// https://github.com/turbolinks/turbolinks/blob/master/src/turbolinks/snapshot.coffee
Turbolinks.Snapshot.fromHTMLElement = function (htmlElement) {
    var bodyElement, headDetails, headElement, _ref;
    headElement = htmlElement.querySelector("head");
    bodyElement = (_ref = htmlElement.querySelector("body")) != null ? _ref : document.createElement("body");
    headDetails = Turbolinks.HeadDetails.fromHeadElement(headElement);
    var snapshot = new this(headDetails, bodyElement, htmlElement.outerHTML);
    snapshot.htmlString = htmlElement.outerHTML;
    return snapshot;
};

Turbolinks.Snapshot.prototype.clone = function () {
    var snapshot = new this.constructor(this.headDetails, this.bodyElement.cloneNode(true));
    snapshot.htmlString = this.htmlString;
    return snapshot;
};

// Source: Converted coffee to JS with: https://awsm-tools.com/code/coffee2js
// https://github.com/turbolinks/turbolinks/blob/master/src/turbolinks/snapshot_cache.coffee
Turbolinks.LocalCache = (function () {
    var keyForLocation;

    function LocalCache(_at_size) {
        this.size = _at_size;
        this.keys = JSON.parse(window.localStorage.getItem('keys')) || [];
    }

    LocalCache.prototype.has = function (location) {
        var key;
        key = keyForLocation(location);
        return window.localStorage.getItem(key) !== null;
    };

    LocalCache.prototype.get = function (location) {
        var snapshot;
        if (!this.has(location)) {
            return;
        }
        snapshot = this.read(location);
        this.touch(location);
        return snapshot;
    };

    LocalCache.prototype.put = function (location, snapshot) {
        this.write(location, snapshot);
        this.touch(location);
        return snapshot;
    };

    LocalCache.prototype.read = function (location) {
        var key;
        key = keyForLocation(location);
        return Turbolinks.Snapshot.wrap(window.localStorage.getItem(key));
    };

    LocalCache.prototype.write = function (location, snapshot) {
        var key;
        key = keyForLocation(location);
        window.localStorage.setItem('keys', JSON.stringify(this.keys));
        return window.localStorage.setItem(key, snapshot.htmlString);
    };

    LocalCache.prototype.touch = function (location) {
        var index, key;
        key = keyForLocation(location);
        index = this.keys.indexOf(key);
        if (index > -1) {
            this.keys.splice(index, 1);
        }
        this.keys.unshift(key);
        return this.trim();
    };

    LocalCache.prototype.trim = function () {
        var key, _i, _len, _ref, _results;
        _ref = this.keys.splice(this.size);
        _results = [];
        for (_i = 0, _len = _ref.length; _i < _len; _i++) {
            key = _ref[_i];
            _results.push(window.localStorage.removeItem(key));
        }
        return _results;
    };

    keyForLocation = function (location) {
        return Turbolinks.Location.wrap(location).toCacheKey();
    };

    return LocalCache;
})();

Turbolinks.controller.cache = new Turbolinks.LocalCache(20);