fix(datetime): fix am/pm in format w/out minutes or seconds

Closes #9269

src/util/datetime-util.ts

@@ -278,7 +278,7 @@ export function updateDate(existingData: DateTimeData, newData: any) {
 
 
 export function parseTemplate(template: string): string[] {
-  let formats: string[] = [];
+  const formats: string[] = [];
 
   template = template.replace(/[^\w\s]/gi, ' ');
 
@@ -288,17 +288,19 @@ export function parseTemplate(template: string): string[] {
     }
   });
 
-  let words = template.split(' ').filter(w => w.length > 0);
+  const words = template.split(' ').filter(w => w.length > 0);
   words.forEach((word, i) => {
     FORMAT_KEYS.forEach(format => {
       if (word === format.f) {
         if (word === FORMAT_A || word === FORMAT_a) {
           // this format is an am/pm format, so it's an "a" or "A"
+          console.log(`word: ${word}, words[i - 1]: ${words[i - 1]}`);
+
           if ((formats.indexOf(FORMAT_h) < 0 && formats.indexOf(FORMAT_hh) < 0) ||
-              (words[i - 1] !== FORMAT_m && words[i - 1] !== FORMAT_mm)) {
+              VALID_AMPM_PREFIX.indexOf(words[i - 1]) === -1) {
             // template does not already have a 12-hour format
-            // or this am/pm format doesn't have a minute format immediately before it
-            // so do not treat this word "a" or "A" as an am/pm format
+            // or this am/pm format doesn't have a hour, minute, or second format immediately before it
+            // so do not treat this word "a" or "A" as the am/pm format
             return;
           }
         }
@@ -515,3 +517,7 @@ const MONTH_SHORT_NAMES = [
   'Nov',
   'Dec',
 ];
+
+const VALID_AMPM_PREFIX = [
+  FORMAT_hh, FORMAT_h, FORMAT_mm, FORMAT_m, FORMAT_ss, FORMAT_s
+];

src/util/test/datetime-util.spec.ts

@@ -321,6 +321,13 @@ describe('parseTemplate', () => {
     expect(formats[2]).toEqual('a');
   });
 
+  it('should allow am/pm when using only 12-hour', () => {
+    var formats = datetime.parseTemplate('hh a');
+    expect(formats.length).toEqual(2);
+    expect(formats[0]).toEqual('hh');
+    expect(formats[1]).toEqual('a');
+  });
+
   it('should allow am/pm when using 12-hour', () => {
     var formats = datetime.parseTemplate('hh:mm a');
     expect(formats.length).toEqual(3);
@@ -329,7 +336,7 @@ describe('parseTemplate', () => {
     expect(formats[2]).toEqual('a');
   });
 
-  it('should not add am/pm when not using 24-hour', () => {
+  it('should not add am/pm when using 24-hour', () => {
     var formats = datetime.parseTemplate('HH:mm a');
     expect(formats.length).toEqual(2);
     expect(formats[0]).toEqual('HH');