Date().toDateString()

As much as I (still) enjoy reading thru the solution, I feel it is "too fat" for casually formatting a date (and time) on BangleJS... BUT: If an application has the subject of date(s) and time(s), then it is most likely already the smallest 'module' for it's comprehensiveness, flexibility and efficiency (w/ @MaBe 's shorter length checker/stretcher).

Here is another - cheap - Date Formatter:

// DF: BangleJS Date Formatter
let DF = // cheap Date Formatter
{ l: null    // last used; for reuse pass -1 for d as date
, f: function(d,p) { // format(optDateOrMillis,optPattern) - 02/29/2020
    var d=this.i(d),s=this.s(p=p||this.p),b;
    return (p.split(s).map(v=>( ((b=((b=v.length)<2)?0:b)?"000":"")
      + this.x[v.charAt(0)](d) ).substr(-b)).join(s) ); }
, d: function(d,ds) { return this.t(d,"n",ds||this.ds); } // d name
, m: function(d,ms) { return this.t(d,"m",ms||this.ms); } // m name
, c: function(d) { return [DF.d(d),DF.m(-1),DF.f(-1,"d y")].join(" "); }
, t: function(d,x,ts){ return ts.split(",")[this.x[x](this.i(d))]; }
, ds: "Sun,Mon,Tue,Wed,Thu,Fri,Sat" // Monday,Tuesday ..."
, ms: ",Jan,Feb,Mar,Apr,May,Jun,Jul,Aug,Sep,Oct,Nov,Dec" // January,...
, p: "mm/dd/yy" // pattern
, x: {m:d=>d.getMonth()+1,d:d=>d.getDate(),y:d=>d.getFullYear()
     ,n:d=>d.getDay()}
, s: function(p) { var s,i=-1,l=p.length; while(++i<l) { // 1st sep
    if ("mdy".indexOf(s=p.charAt(i))<0) return s; } return"/"; }
, i: function(d) { // ret Date as is, today, from millis or last used
    return this.l = (isNaN(d)||d=="") ? d||new Date()
      : (d<0) ? this.l : new Date(d); }
};

Usage:

02/15/20 - DF.f() today
2/15 - DF.f(-1,"m/d") from used
15.2. - DF.f("","m.d")+"." today
2020-02-15 - DF.f(null,"yyyy-mm-dd") today
Sat Feb 15, 2020 - DF.d(),DF.m(-1),DF.f(-1,"d")+",",DF.f(-1,"y")
Sat Feb 15 2020 - DF.d(),DF.m(-1),DF.f(-1,"d y")
Sat Feb 15 2020 - DF.c() - today, combined, like Date.toString()
Sat Feb 15 2020 - DF.l.toString().substr(0,15) - today from used
Sat Feb 15 2020 08:49:34 GMT-0800 (Pacific Standard Time) - DF.i(-1) - today from last used
Sat Feb 15 2020 08:49:34 GMT-0800 (Pacific Standard Time) - DF.l - today from used

Attached .html file can be directly executed to run formatter and example in browser. It can also be downloaded, modified, and played with.

The formatter can be modularized and then composed with a base module and extended with - for example - the week day and month names and combined formatting functions - and last but not lest - with the time formatting functions.

The base module with just the number formatter is very compact and looks then like this:

let DF = // cheap Date Formatter
{ l: null    // last used; for reuse pass -1 for d as date
, f: function(d,p) { // format(optDateOrMillis,optPattern) - 02/29/2020
    var d=this.i(d),s=this.s(p=p||this.p),b;
    return (p.split(s).map(v=>( ((b=((b=v.length)<2)?0:b)?"000":"")
      + this.x[v.charAt(0)](d) ).substr(-b)).join(s) ); }
, p: "mm/dd/yy" // pattern
, x: {m:d=>d.getMonth()+1,d:d=>d.getDate(),y:d=>d.getFullYear() }
, s: function(p) { var s,i=-1,l=p.length; while(++i<l) { // 1st sep
    if ("mdy".indexOf(s=p.charAt(i))<0) return s; } return"/"; }
, i: function(d) { // ret Date as is, today, from millis or last used
    return this.l=(isNaN(d)||d=="")?d||new Date():(d<0)?this.l:new Date(d);}
};

1 Attachment

• DF.html