The section of Chipotle's checkout javascript that is doing form validation.

chipotle-checkout.js

, function(e, t) {
    var a = Math.abs;
    (function() {
        'use strict';
        angular.module('ui.mask', []).value('uiMaskConfig', {
            maskDefinitions: {
                9: /\d/,
                A: /[a-zA-Z]/,
                "*": /[a-zA-Z0-9]/
            },
            clearOnBlur: !0,
            clearOnBlurPlaceholder: !1,
            escChar: '\\',
            eventsToHandle: ['input', 'keyup', 'click', 'focus'],
            addDefaultPlaceholder: !0,
            allowInvalidValue: !1
        }).provider('uiMask.Config', function() {
            var e = {};
            this.maskDefinitions = function(t) {
                return e.maskDefinitions = t
            }
            ,
            this.clearOnBlur = function(t) {
                return e.clearOnBlur = t
            }
            ,
            this.clearOnBlurPlaceholder = function(t) {
                return e.clearOnBlurPlaceholder = t
            }
            ,
            this.eventsToHandle = function(t) {
                return e.eventsToHandle = t
            }
            ,
            this.addDefaultPlaceholder = function(t) {
                return e.addDefaultPlaceholder = t
            }
            ,
            this.allowInvalidValue = function(t) {
                return e.allowInvalidValue = t
            }
            ,
            this.$get = ['uiMaskConfig', function(t) {
                var a = t;
                for (var r in e)
                    angular.isObject(e[r]) && !angular.isArray(e[r]) ? angular.extend(a[r], e[r]) : a[r] = e[r];
                return a
            }
            ]
        }).directive('uiMask', ['uiMask.Config', function(e) {
            function t(e) {
                return e === document.activeElement && (!document.hasFocus || document.hasFocus()) && !!(e.type || e.href || ~e.tabIndex)
            }
            return {
                priority: 100,
                require: 'ngModel',
                restrict: 'A',
                compile: function r() {
                    var n = angular.copy(e);
                    return function e(r, o, l, i) {
                        function s(e) {
                            return angular.isDefined(e) ? (E(e),
                            !P) ? u() : (g(),
                            h(),
                            !0) : u()
                        }
                        function d(e) {
                            !e || (B = e,
                            P && !(0 === o.val().length && angular.isDefined(l.placeholder)) && o.val(y(b(o.val()))))
                        }
                        function c() {
                            return s(l.uiMask)
                        }
                        function m(e) {
                            return P ? (z = b(e || ''),
                            V = v(z),
                            i.$setValidity('mask', V),
                            z.length ? V || Q.allowInvalidValue ? y(z) : void 0 : void 0) : e
                        }
                        function p(e) {
                            return P ? (z = b(e || ''),
                            V = v(z),
                            i.$viewValue = z.length ? y(z) : '',
                            i.$setValidity('mask', V),
                            V || Q.allowInvalidValue) ? J ? i.$viewValue : z : void 0 : e
                        }
                        function u() {
                            return P = !1,
                            f(),
                            angular.isDefined(N) ? o.attr('placeholder', N) : o.removeAttr('placeholder'),
                            angular.isDefined(R) ? o.attr('maxlength', R) : o.removeAttr('maxlength'),
                            o.val(i.$modelValue),
                            i.$viewValue = i.$modelValue,
                            !1
                        }
                        function g() {
                            z = W = b(i.$modelValue || ''),
                            q = G = y(z),
                            V = v(z),
                            l.maxlength && o.attr('maxlength', 2 * j[j.length - 1]),
                            !N && Q.addDefaultPlaceholder && o.attr('placeholder', B);
                            for (var e = i.$modelValue, t = i.$formatters.length; t--; )
                                e = i.$formatters[t](e);
                            i.$viewValue = e || '',
                            i.$render()
                        }
                        function h() {
                            D || (o.bind('blur', C),
                            o.bind('mousedown mouseup', k),
                            o.bind('keydown', M),
                            o.bind(Q.eventsToHandle.join(' '), S),
                            D = !0)
                        }
                        function f() {
                            !D || (o.unbind('blur', C),
                            o.unbind('mousedown', k),
                            o.unbind('mouseup', k),
                            o.unbind('keydown', M),
                            o.unbind('input', S),
                            o.unbind('keyup', S),
                            o.unbind('click', S),
                            o.unbind('focus', S),
                            D = !1)
                        }
                        function v(e) {
                            return !e.length || e.length >= U
                        }
                        function b(e) {
                            var t = '', a = o[0], r = H.slice(), n = Y, i = n + O(a), l = '', s, d;
                            return e = e.toString(),
                            s = 0,
                            d = e.length - B.length,
                            angular.forEach(F, function(t) {
                                var a = t.position;
                                !(a >= n && a < i) && (a >= n && (a += d),
                                e.substring(a, a + t.value.length) === t.value && (l += e.slice(s, a),
                                s = a + t.value.length))
                            }),
                            e = l + e.slice(s),
                            angular.forEach(e.split(''), function(e) {
                                r.length && r[0].test(e) && (t += e,
                                r.shift())
                            }),
                            t
                        }
                        function y(e) {
                            var t = ''
                              , a = j.slice();
                            return angular.forEach(B.split(''), function(r, n) {
                                e.length && n === a[0] ? (t += e.charAt(0) || '_',
                                e = e.substr(1),
                                a.shift()) : t += r
                            }),
                            t
                        }
                        function $(e) {
                            var t = angular.isDefined(l.uiMaskPlaceholder) ? l.uiMaskPlaceholder : l.placeholder, a;
                            return angular.isDefined(t) && t[e] ? t[e] : (a = angular.isDefined(l.uiMaskPlaceholderChar) && l.uiMaskPlaceholderChar ? l.uiMaskPlaceholderChar : '_',
                            'space' === a.toLowerCase() ? ' ' : a[0])
                        }
                        function w() {
                            var e = B.split(''), t, a;
                            j && !isNaN(j[0]) && angular.forEach(j, function(t) {
                                e[t] = '_'
                            }),
                            t = e.join(''),
                            a = t.replace(/[_]+/g, '_').split('_'),
                            a = a.filter(function(e) {
                                return '' !== e
                            });
                            var r = 0;
                            return a.map(function(e) {
                                var a = t.indexOf(e, r);
                                return r = a + 1,
                                {
                                    value: e,
                                    position: a
                                }
                            })
                        }
                        function E(e) {
                            var t = 0;
                            if (j = [],
                            H = [],
                            B = '',
                            angular.isString(e)) {
                                U = 0;
                                var a = !1
                                  , r = 0
                                  , n = e.split('')
                                  , o = !1;
                                angular.forEach(n, function(e, n) {
                                    o ? (o = !1,
                                    B += e,
                                    t++) : Q.escChar === e ? o = !0 : Q.maskDefinitions[e] ? (j.push(t),
                                    B += $(n - r),
                                    H.push(Q.maskDefinitions[e]),
                                    t++,
                                    !a && U++,
                                    a = !1) : '?' === e ? (a = !0,
                                    r++) : (B += e,
                                    t++)
                                })
                            }
                            j.push(j.slice().pop() + 1),
                            F = w(),
                            P = !!(1 < j.length)
                        }
                        function C() {
                            if ((Q.clearOnBlur || Q.clearOnBlurPlaceholder && 0 === z.length && l.placeholder) && (Y = 0,
                            K = 0,
                            (!V || 0 === z.length) && (q = '',
                            o.val(''),
                            r.$apply(function() {
                                !i.$pristine && i.$setViewValue('')
                            }))),
                            z !== Z) {
                                var e = o.val()
                                  , t = '' === z && e && angular.isDefined(l.uiMaskPlaceholderChar) && 'space' === l.uiMaskPlaceholderChar;
                                t && o.val(''),
                                x(o[0]),
                                t && o.val(e)
                            }
                            Z = z
                        }
                        function x(e) {
                            var t;
                            angular.isFunction(window.Event) && !e.fireEvent ? (t = new Event('change',{
                                view: window,
                                bubbles: !0,
                                cancelable: !1
                            }),
                            e.dispatchEvent(t)) : 'createEvent'in document ? (t = document.createEvent('HTMLEvents'),
                            t.initEvent('change', !1, !0),
                            e.dispatchEvent(t)) : e.fireEvent && e.fireEvent('onchange')
                        }
                        function k(t) {
                            'mousedown' === t.type ? o.bind('mouseout', T) : o.unbind('mouseout', T)
                        }
                        function T() {
                            K = O(this),
                            o.unbind('mouseout', T)
                        }
                        function M(t) {
                            var e = 8 === t.which
                              , a = A(this) - 1 || 0
                              , r = 90 === t.which && t.ctrlKey;
                            if (e) {
                                for (; 0 <= a; ) {
                                    if (_(a)) {
                                        I(this, a + 1);
                                        break
                                    }
                                    a--
                                }
                                X = -1 == a
                            }
                            r && (o.val(''),
                            t.preventDefault())
                        }
                        function S(t) {
                            t = t || {};
                            var e = t.which
                              , a = t.type;
                            if (16 !== e && 91 !== e) {
                                var n = o.val(), l = G, s = !1, d = b(n), c = W, m = A(this) || 0, p = Y || 0, u = m - p, g = j[0], h = j[d.length] || j.slice().shift(), f = K || 0, v = 0 < O(this), $ = 0 < f, w = n.length > l.length || f && n.length > l.length - f, E = n.length < l.length || f && n.length === l.length - f, C = 37 <= e && 40 >= e && t.shiftKey, x = 37 === e, k = 8 === e || 'keyup' !== a && E && -1 == u, T = 46 === e || 'keyup' !== a && E && 0 == u && !$, M = (x || k || 'click' === a) && m > g, S;
                                if (K = O(this),
                                !(C || v && ('click' === a || 'keyup' === a || 'focus' === a))) {
                                    if (k && X)
                                        return o.val(B),
                                        r.$apply(function() {
                                            i.$setViewValue('')
                                        }),
                                        void I(this, p);
                                    if ('input' === a && E && !$ && d === c) {
                                        for (; k && m > g && !_(m); )
                                            m--;
                                        for (; T && m < h && -1 === j.indexOf(m); )
                                            m++;
                                        var P = j.indexOf(m);
                                        d = d.substring(0, P) + d.substring(P + 1),
                                        d !== c && (s = !0)
                                    }
                                    for (S = y(d),
                                    G = S,
                                    W = d,
                                    !s && n.length > S.length && (s = !0),
                                    o.val(S),
                                    s && r.$apply(function() {
                                        i.$setViewValue(S)
                                    }),
                                    w && m <= g && (m = g + 1),
                                    M && m--,
                                    m = m > h ? h : m < g ? g : m; !_(m) && m > g && m < h; )
                                        m += M ? -1 : 1;
                                    (M && m < h || w && !_(p)) && m++,
                                    Y = m,
                                    I(this, m)
                                }
                            }
                        }
                        function _(e) {
                            return -1 < j.indexOf(e)
                        }
                        function A(e) {
                            if (!e)
                                return 0;
                            if (void 0 !== e.selectionStart)
                                return e.selectionStart;
                            if (document.selection && t(o[0])) {
                                e.focus();
                                var a = document.selection.createRange();
                                return a.moveStart('character', e.value ? -e.value.length : 0),
                                a.text.length
                            }
                            return 0
                        }
                        function I(e, a) {
                            if (!e)
                                return 0;
                            if (0 !== e.offsetWidth && 0 !== e.offsetHeight)
                                if (e.setSelectionRange)
                                    t(o[0]) && (e.focus(),
                                    e.setSelectionRange(a, a));
                                else if (e.createTextRange) {
                                    var r = e.createTextRange();
                                    r.collapse(!0),
                                    r.moveEnd('character', a),
                                    r.moveStart('character', a),
                                    r.select()
                                }
                        }
                        function O(e) {
                            return e ? void 0 === e.selectionStart ? window.getSelection ? window.getSelection().toString().length : document.selection ? document.selection.createRange().text.length : 0 : e.selectionEnd - e.selectionStart : 0
                        }
                        var P = !1, D = !1, N = l.placeholder, R = l.maxlength, L = i.$isEmpty, j, H, B, F, U, z, q, V, G, W, Y, K, X;
                        i.$isEmpty = function(e) {
                            return P ? L(b(e || '')) : L(e)
                        }
                        ;
                        var J = !1;
                        l.$observe('modelViewValue', function(e) {
                            'true' === e && (J = !0)
                        }),
                        l.$observe('allowInvalidValue', function(e) {
                            Q.allowInvalidValue = !('' !== e) || !!e,
                            m(i.$modelValue)
                        });
                        var Q = {};
                        l.uiOptions ? (Q = r.$eval('[' + l.uiOptions + ']'),
                        Q = angular.isObject(Q[0]) ? function(e, t) {
                            for (var a in e)
                                Object.prototype.hasOwnProperty.call(e, a) && (void 0 === t[a] ? t[a] = angular.copy(e[a]) : angular.isObject(t[a]) && !angular.isArray(t[a]) && (t[a] = angular.extend({}, e[a], t[a])));
                            return t
                        }(n, Q[0]) : n) : Q = n,
                        l.$observe('uiMask', s),
                        angular.isDefined(l.uiMaskPlaceholder) ? l.$observe('uiMaskPlaceholder', d) : l.$observe('placeholder', d),
                        angular.isDefined(l.uiMaskPlaceholderChar) && l.$observe('uiMaskPlaceholderChar', c),
                        i.$formatters.unshift(m),
                        i.$parsers.unshift(p);
                        var Z = o.val();
                        o.bind('mousedown mouseup', k),
                        !Array.prototype.indexOf && (Array.prototype.indexOf = function(e) {
                            if (null === this)
                                throw new TypeError;
                            var r = Object(this)
                              , t = r.length >>> 0;
                            if (0 == t)
                                return -1;
                            var o = 0;
                            if (1 < arguments.length && (o = +arguments[1],
                            o == o ? 0 != o && o != Infinity && o != -Infinity && (o = (0 < o || -1) * Math.floor(a(o))) : o = 0),
                            o >= t)
                                return -1;
                            for (var n = 0 <= o ? o : Math.max(t - a(o), 0); n < t; n++)
                                if (n in r && r[n] === e)
                                    return n;
                            return -1
                        }
                        )
                    }
                }
            }
        }
        ])
    }
    )()
}