Travis build: 1300

README.md

@@ -252,6 +252,7 @@ _30s.average(1, 2, 3);
 * [`maxDate`](#maxdate)
 * [`minDate`](#mindate)
 * [`tomorrow`](#tomorrow)
+* [`yesterday`](#yesterday)
 
 </details>
 
@@ -4579,6 +4580,32 @@ tomorrow(); // 2018-10-19 (if current date is 2018-10-18)
 
 <br>[⬆ Back to top](#contents)
 
+### yesterday
+
+Results in a string representation of yesterday's date.
+
+Use `new Date()` to get the current date, decrement by one using `Date.getDate()` and set the value to the result using `Date.setDate()`.
+Use `Date.prototype.toISOString()` to return a string in `yyyy-mm-dd` format.
+
+```js
+const yesterday = () => {
+  let t = new Date();
+  t.setDate(t.getDate() - 1);
+  return t.toISOString().split('T')[0];
+};
+```
+
+<details>
+<summary>Examples</summary>
+
+```js
+yesterday(); // 2018-10-17 (if current date is 2018-10-18)
+```
+
+</details>
+
+<br>[⬆ Back to top](#contents)
+
 
 ---
 
@@ -4736,6 +4763,7 @@ const checkProp = (predicate, prop) => obj => !!predicate(obj[prop]);
 
 
 
+
 const lengthIs4 = checkProp(l => l === 4, 'length');
 lengthIs4([]); // false
 lengthIs4([1,2,3,4]); // true

docs/about.html

@@ -291,6 +291,7 @@
 <li><a tags="date,math,beginner" href="./date#maxdate">maxDate</a></li>
 <li><a tags="date,math,beginner" href="./date#mindate">minDate</a></li>
 <li><a tags="date,intermediate" href="./date#tomorrow">tomorrow</a></li>
+<li><a tags="date,intermediate" href="./date#yesterday">yesterday</a></li>
 </ul>
 <h4 class="collapse">Function
 </h4><ul><li><a tags="function,intermediate" href="./function#attempt">attempt</a></li>

docs/contributing.html

@@ -291,6 +291,7 @@
 <li><a tags="date,math,beginner" href="./date#maxdate">maxDate</a></li>
 <li><a tags="date,math,beginner" href="./date#mindate">minDate</a></li>
 <li><a tags="date,intermediate" href="./date#tomorrow">tomorrow</a></li>
+<li><a tags="date,intermediate" href="./date#yesterday">yesterday</a></li>
 </ul>
 <h4 class="collapse">Function
 </h4><ul><li><a tags="function,intermediate" href="./function#attempt">attempt</a></li>

snippets/checkProp.md

@@ -19,6 +19,7 @@ const checkProp = (predicate, prop) => obj => !!predicate(obj[prop]);
 
 
 
+
 const lengthIs4 = checkProp(l => l === 4, 'length');
 lengthIs4([]); // false
 lengthIs4([1,2,3,4]); // true