diff --git a/README.md b/README.md index 1a2e91391..979531a63 100644 --- a/README.md +++ b/README.md @@ -1201,8 +1201,9 @@ Returns the remaining elements. ```js const dropRightWhile = (arr, func) => { - while (arr.length > 0 && !func(arr[arr.length - 1])) arr = arr.slice(0, -1); - return arr; + let rightIndex = arr.length; + while (rightIndex-- && !func(arr[rightIndex])); + return arr.slice(0, rightIndex + 1); }; ``` @@ -4736,6 +4737,7 @@ const checkProp = (predicate, prop) => obj => !!predicate(obj[prop]); + const lengthIs4 = checkProp(l => l === 4, 'length'); lengthIs4([]); // false lengthIs4([1,2,3,4]); // true diff --git a/docs/function.html b/docs/function.html index 6c6291409..efccc0759 100644 --- a/docs/function.html +++ b/docs/function.html @@ -154,6 +154,7 @@ console.log< + const lengthIs4 = checkProp(l => l === 4, 'length'); lengthIs4([]); // false lengthIs4([1,2,3,4]); // true diff --git a/docs/index.html b/docs/index.html index d30f1e12a..dde596844 100644 --- a/docs/index.html +++ b/docs/index.html @@ -155,8 +155,9 @@ dropRight([1, 2, 3], 2); // [1] dropRight([1, 2, 3], 42); // []

dropRightWhile

Removes elements from the end of an array until the passed function returns true. Returns the remaining elements in the array.

Loop through the array, using Array.prototype.slice() to drop the last element of the array until the returned value from the function is true. Returns the remaining elements.

const dropRightWhile = (arr, func) => {
-  while (arr.length > 0 && !func(arr[arr.length - 1])) arr = arr.slice(0, -1);
-  return arr;
+  let rightIndex = arr.length;
+  while (rightIndex-- && !func(arr[rightIndex]));
+  return arr.slice(0, rightIndex + 1);
 };
 
dropRightWhile([1, 2, 3, 4], n => n < 3); // [1, 2]

dropWhile

Removes elements in an array until the passed function returns true. Returns the remaining elements in the array.

Loop through the array, using Array.prototype.slice() to drop the first element of the array until the returned value from the function is true. Returns the remaining elements.

const dropWhile = (arr, func) => {
diff --git a/snippets/checkProp.md b/snippets/checkProp.md
index 86a412cee..391d872d6 100644
--- a/snippets/checkProp.md
+++ b/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
diff --git a/test/_30s.js b/test/_30s.js
index 1be8796e9..4151e82bd 100644
--- a/test/_30s.js
+++ b/test/_30s.js
@@ -279,8 +279,9 @@ const distance = (x0, y0, x1, y1) => Math.hypot(x1 - x0, y1 - y0);
 const drop = (arr, n = 1) => arr.slice(n);
 const dropRight = (arr, n = 1) => arr.slice(0, -n);
 const dropRightWhile = (arr, func) => {
-  while (arr.length > 0 && !func(arr[arr.length - 1])) arr = arr.slice(0, -1);
-  return arr;
+  let rightIndex = arr.length;
+  while (rightIndex-- && !func(arr[rightIndex]));
+  return arr.slice(0, rightIndex + 1);
 };
 const dropWhile = (arr, func) => {
   while (arr.length > 0 && !func(arr[0])) arr = arr.slice(1);