Automated rollback of commit 9bd3a15.

PiperOrigin-RevId: 413057968
Change-Id: Ibf9f714e367c8cd990d25d58f3ca15d903f790d2

closure/goog/string/string.js

@@ -1120,6 +1120,27 @@ goog.string.makeSafe = function(obj) {
   return obj == null ? '' : String(obj);
 };
 
+
+/**
+ * Concatenates string expressions. This is useful
+ * since some browsers are very inefficient when it comes to using plus to
+ * concat strings. Be careful when using null and undefined here since
+ * these will not be included in the result. If you need to represent these
+ * be sure to cast the argument to a String first.
+ * For example:
+ * <pre>buildString('a', 'b', 'c', 'd') -> 'abcd'
+ * buildString(null, undefined) -> ''
+ * </pre>
+ * @param {...*} var_args A list of strings to concatenate. If not a string,
+ *     it will be casted to one.
+ * @return {string} The concatenation of `var_args`.
+ */
+goog.string.buildString = function(var_args) {
+  'use strict';
+  return Array.prototype.join.call(arguments, '');
+};
+
+
 /**
  * Returns a string with at least 64-bits of randomness.
  *

closure/goog/string/string_test.js

@@ -1036,6 +1036,18 @@ testSuite({
     assertEquals('foofoofoofoofoofoo', googString.repeat('foo', 6));
   },
 
+  testBuildString() {
+    assertEquals('', googString.buildString());
+    assertEquals('a', googString.buildString('a'));
+    assertEquals('ab', googString.buildString('ab'));
+    assertEquals('ab', googString.buildString('a', 'b'));
+    assertEquals('abcd', googString.buildString('a', 'b', 'c', 'd'));
+    assertEquals('0', googString.buildString(0));
+    assertEquals('0123', googString.buildString(0, 1, 2, 3));
+    assertEquals('ab01', googString.buildString('a', 'b', 0, 1));
+    assertEquals('', googString.buildString(null, undefined));
+  },
+
   testCompareVersions() {
     const f = googString.compareVersions;
     assertTrue('numeric equality broken', f(1, 1) == 0);