根据时间戳及想要的时间格式装换出时间的js函数

使用效果

date("Y-m-d",1543920494)  2018-12-04
date("Y-m-d H:i:s",1543920494)  2018-12-04 18:48:14

功能代码

function date(format, timestamp) {
        var a, jsdate = ((timestamp) ? new Date(timestamp * 1000) : new Date());
        var pad = function (n, c) {
            if ((n = n + "").length < c) {
                return new Array(++c - n.length).join("0") + n;
            } else {
                return n;
            }
        };
        var txt_weekdays = ["Sunday", "Monday", "Tuesday", "Wednesday", "Thursday", "Friday", "Saturday"];
        var txt_ordin = { 1: "st", 2: "nd", 3: "rd", 21: "st", 22: "nd", 23: "rd", 31: "st" };
        var txt_months = ["", "January", "February", "March", "April", "May", "June", "July", "August", "September", "October", "November", "December"];
        var f = {
            // Day 
            d: function () { return pad(f.j(), 2) },
            D: function () { return f.l().substr(0, 3) },
            j: function () { return jsdate.getDate() },
            l: function () { return txt_weekdays[f.w()] },
            N: function () { return f.w() + 1 },
            S: function () { return txt_ordin[f.j()] ? txt_ordin[f.j()] : 'th' },
            w: function () { return jsdate.getDay() },
            z: function () { return (jsdate - new Date(jsdate.getFullYear() + "/1/1")) / 864e5 >> 0 },

            // Week 
            W: function () {
                var a = f.z(), b = 364 + f.L() - a;
                var nd2, nd = (new Date(jsdate.getFullYear() + "/1/1").getDay() || 7) - 1;
                if (b <= 2 && ((jsdate.getDay() || 7) - 1) <= 2 - b) {
                    return 1;
                } else {
                    if (a <= 2 && nd >= 4 && a >= (6 - nd)) {
                        nd2 = new Date(jsdate.getFullYear() - 1 + "/12/31");
                        return date("W", Math.round(nd2.getTime() / 1000));
                    } else {
                        return (1 + (nd <= 3 ? ((a + nd) / 7) : (a - (7 - nd)) / 7) >> 0);
                    }
                }
            },

            // Month 
            F: function () { return txt_months[f.n()] },
            m: function () { return pad(f.n(), 2) },
            M: function () { return f.F().substr(0, 3) },
            n: function () { return jsdate.getMonth() + 1 },
            t: function () {
                var n;
                if ((n = jsdate.getMonth() + 1) == 2) {
                    return 28 + f.L();
                } else {
                    if (n & 1 && n < 8 || !(n & 1) && n > 7) {
                        return 31;
                    } else {
                        return 30;
                    }
                }
            },

            // Year 
            L: function () { var y = f.Y(); return (!(y & 3) && (y % 1e2 || !(y % 4e2))) ? 1 : 0 },
            //o not supported yet 
            Y: function () { return jsdate.getFullYear() },
            y: function () { return (jsdate.getFullYear() + "").slice(2) },

            // Time 
            a: function () { return jsdate.getHours() > 11 ? "pm" : "am" },
            A: function () { return f.a().toUpperCase() },
            B: function () {
                // peter paul koch: 
                var off = (jsdate.getTimezoneOffset() + 60) * 60;
                var theSeconds = (jsdate.getHours() * 3600) + (jsdate.getMinutes() * 60) + jsdate.getSeconds() + off;
                var beat = Math.floor(theSeconds / 86.4);
                if (beat > 1000) beat -= 1000;
                if (beat < 0) beat += 1000;
                if ((String(beat)).length == 1) beat = "00" + beat;
                if ((String(beat)).length == 2) beat = "0" + beat;
                return beat;
            },
            g: function () { return jsdate.getHours() % 12 || 12 },
            G: function () { return jsdate.getHours() },
            h: function () { return pad(f.g(), 2) },
            H: function () { return pad(jsdate.getHours(), 2) },
            i: function () { return pad(jsdate.getMinutes(), 2) },
            s: function () { return pad(jsdate.getSeconds(), 2) },
            //u not supported yet 

            // Timezone 
            //e not supported yet 
            //I not supported yet 
            O: function () {
                var t = pad(Math.abs(jsdate.getTimezoneOffset() / 60 * 100), 4);
                if (jsdate.getTimezoneOffset() > 0) t = "-" + t; else t = "+" + t;
                return t;
            },
            P: function () { var O = f.O(); return (O.substr(0, 3) + ":" + O.substr(3, 2)) },
            //T not supported yet 
            //Z not supported yet 

            // Full Date/Time 
            c: function () { return f.Y() + "-" + f.m() + "-" + f.d() + "T" + f.h() + ":" + f.i() + ":" + f.s() + f.P() },
            //r not supported yet 
            U: function () { return Math.round(jsdate.getTime() / 1000) }
        };

        return format.replace(/[\\]?([a-zA-Z])/g, function (t, s) {
            if (t != s) {
                // escaped 
                ret = s;
            } else if (f[s]) {
                // a date function exists 
                ret = f[s]();
            } else {
                // nothing special 
                ret = s;
            }
            return ret;
        });
    }