LibJS: Add Array.prototype.forEach()

Author: https://github.com/linusg
Commit: 866172a721
Pull-request: https://github.com/SerenityOS/serenity/pull/1793

Libraries/LibJS/Tests/Array.prototype.forEach.js

@@ -0,0 +1,64 @@
+load("test-common.js");
+
+try {
+    assert(Array.prototype.forEach.length === 1);
+
+    try {
+        [].forEach();
+        assertNotReached();
+    } catch (e) {
+        assert(e.name === "TypeError");
+        assert(e.message === "Array.prototype.forEach() requires at least one argument");
+    }
+
+    try {
+        [].forEach(undefined);
+        assertNotReached();
+    } catch (e) {
+        assert(e.name === "TypeError");
+        assert(e.message === "undefined is not a function");
+    }
+
+    var a = [1, 2, 3];
+    var o = {};
+    var callbackCalled = 0;
+    var callback = () => { callbackCalled++; };
+
+    assert([].forEach(callback) === undefined);
+    assert(callbackCalled === 0);
+
+    assert(a.forEach(callback) === undefined);
+    assert(callbackCalled === 3);
+
+    callbackCalled = 0;
+    a.forEach(function(value, index) {
+        assert(value === a[index]);
+        assert(index === a[index] - 1);
+    });
+
+    callbackCalled = 0;
+    a.forEach(function(_, _, array) {
+        callbackCalled++;
+        assert(a.length === array.length);
+        a.push("test");
+    });
+    assert(callbackCalled === 3);
+    assert(a.length === 6);
+
+    callbackCalled = 0;
+    a.forEach(function(value, index) {
+        callbackCalled++;
+        this[index] = value;
+    }, o);
+    assert(callbackCalled === 6);
+    assert(o[0] === 1);
+    assert(o[1] === 2);
+    assert(o[2] === 3);
+    assert(o[3] === "test");
+    assert(o[4] === "test");
+    assert(o[5] === "test");
+
+    console.log("PASS");
+} catch (e) {
+    console.log("FAIL: " + e);
+}