Added array reverse (#695)

devs/run-tests/24arraymap.ts

@@ -220,6 +220,14 @@ function testArrayKeys() {
     }
 }
 
+function testArrayReverse() {
+    const array = ['one', 'two', 'three'];
+
+    const reversed = array.reverse();
+    assert(reversed.join() === 'three,two,one', "reversed");
+    assert(array.join() === 'three,two,one', "reversedDestructive");
+}
+
 testArraySome()
 testArrayEvery()
 testArrayFill()
@@ -236,3 +244,4 @@ testArrayAt()
 testArrayWith()
 testArraySort()
 testArrayKeys()
+testArrayReverse()

packages/core/src/array.ts

@@ -215,6 +215,22 @@ Array.prototype.keys = function () {
     return Array(this.length).fill(0).map((_, i) => i);
 }
 
+Array.prototype.reverse = function () {
+    const len = this.length;
+    const middle = Math.floor(len / 2);
+    let lower = 0;
+
+    while (lower !== middle) {
+        const upper = len - lower - 1;
+        const lowerValue = this[lower];
+        this[lower] = this[upper];
+        this[upper] = lowerValue;
+        lower++;
+    }
+    return this;
+}
+
+
 Buffer.prototype.set = function (other: Buffer, trgOff?: number) {
     if (!trgOff) trgOff = 0
     this.blitAt(trgOff, other, 0, other.length)

packages/core/src/corelib.d.ts

@@ -259,6 +259,12 @@ interface Array<T> {
      */
     lastIndexOf(searchElement: T, fromIndex?: number): number
 
+    /**
+     * Reverses the elements in an array in place.
+     * This method mutates the array and returns a reference to the same array.
+     */
+    reverse(): T[]
+
     /**
      * Returns a copy of a section of an array.
      * For both start and end, a negative index can be used to indicate an offset from the end of the array.