https://camaramirassol.sp.gov.br/Scripts/AltoContraste/js/high-contrast.js

1(function () {
2    var Contrast = {
3        storage: 'contrastState',
4        cssClass: 'contrast',
5        currentState: null,
6        check: checkContrast,
7        getState: getContrastState,
8        setState: setContrastState,
9        toogle: toogleContrast,
10        updateView: updateViewContrast
11    };
12
13    window.toggleContrast = function () { Contrast.toogle(); };
14
15    if (document.body) {
16        Contrast.check();
17    } else {
18        document.addEventListener('DOMContentLoaded', function () {
19            Contrast.check();
20        });
21    }
22
23    function checkContrast() {
24        this.updateView();
25    }
26
27    function getContrastState() {
28        return localStorage.getItem(this.storage) === 'true';
29    }
30
31    function setContrastState(state) {
32        localStorage.setItem(this.storage, '' + state);
33        this.currentState = state;
34        this.updateView();
35    }
36
37    function updateViewContrast() {
38        var body = document.body;
39        if (!body) return;
40
41        if (this.currentState === null)
42            this.currentState = this.getState();
43
44        if (this.currentState)
45            body.classList.add(this.cssClass);
46        else
47            body.classList.remove(this.cssClass);
48    }
49
50    function toogleContrast() {
51        this.setState(!this.currentState);
52    }
53})();