chore: Make startsWith faster (#6118)

by using built-in function (polyfill will handle IE).

core/touch.js

@@ -15,7 +15,6 @@
  */
 goog.module('Blockly.Touch');
 
-const utilsString = goog.require('Blockly.utils.string');
 /* eslint-disable-next-line no-unused-vars */
 const {Gesture} = goog.requireType('Blockly.Gesture');
 const {globalThis} = goog.require('Blockly.utils.global');
@@ -246,7 +245,7 @@ exports.checkTouchIdentifier = checkTouchIdentifier;
  * @alias Blockly.Touch.setClientFromTouch
  */
 const setClientFromTouch = function(e) {
-  if (utilsString.startsWith(e.type, 'touch') && e.changedTouches) {
+  if (e.type.startsWith('touch') && e.changedTouches) {
     // Map the touch event's properties to the event.
     const touchPoint = e.changedTouches[0];
     e.clientX = touchPoint.clientX;
@@ -263,9 +262,8 @@ exports.setClientFromTouch = setClientFromTouch;
  * @alias Blockly.Touch.isMouseOrTouchEvent
  */
 const isMouseOrTouchEvent = function(e) {
-  return utilsString.startsWith(e.type, 'touch') ||
-      utilsString.startsWith(e.type, 'mouse') ||
-      utilsString.startsWith(e.type, 'pointer');
+  return e.type.startsWith('touch') || e.type.startsWith('mouse') ||
+      e.type.startsWith('pointer');
 };
 exports.isMouseOrTouchEvent = isMouseOrTouchEvent;
 
@@ -276,8 +274,7 @@ exports.isMouseOrTouchEvent = isMouseOrTouchEvent;
  * @alias Blockly.Touch.isTouchEvent
  */
 const isTouchEvent = function(e) {
-  return utilsString.startsWith(e.type, 'touch') ||
-      utilsString.startsWith(e.type, 'pointer');
+  return e.type.startsWith('touch') || e.type.startsWith('pointer');
 };
 exports.isTouchEvent = isTouchEvent;
 

core/utils/parsing.js

@@ -15,7 +15,6 @@
 goog.module('Blockly.utils.parsing');
 
 const colourUtils = goog.require('Blockly.utils.colour');
-const stringUtils = goog.require('Blockly.utils.string');
 const {Msg} = goog.require('Blockly.Msg');
 
 
@@ -97,9 +96,8 @@ const tokenizeInterpolationInternal = function(
           // BKY_ is the prefix used to namespace the strings used in Blockly
           // core files and the predefined blocks in ../blocks/.
           // These strings are defined in ../msgs/ files.
-          const bklyKey = stringUtils.startsWith(keyUpper, 'BKY_') ?
-              keyUpper.substring(4) :
-              null;
+          const bklyKey =
+              keyUpper.startsWith('BKY_') ? keyUpper.substring(4) : null;
           if (bklyKey && bklyKey in Msg) {
             const rawValue = Msg[bklyKey];
             if (typeof rawValue === 'string') {

core/utils/string.js

@@ -19,17 +19,22 @@
  */
 goog.module('Blockly.utils.string');
 
+const deprecation = goog.require('Blockly.utils.deprecation');
+
 
 /**
- * Fast prefix-checker.
- * Copied from Closure's goog.string.startsWith.
+ * Obsolete prefix-checker.
  * @param {string} str The string to check.
  * @param {string} prefix A string to look for at the start of `str`.
  * @return {boolean} True if `str` begins with `prefix`.
  * @alias Blockly.utils.string.startsWith
+ * @deprecated April 2022. Use built-in string.startsWith.
  */
 const startsWith = function(str, prefix) {
-  return str.lastIndexOf(prefix, 0) === 0;
+  deprecation.warn(
+      'Blockly.utils.string.startsWith()', 'April 2022', 'April 2023',
+      'Use built-in string.startsWith');
+  return str.startsWith(prefix);
 };
 exports.startsWith = startsWith;