Add cls command to repl

doc/api/repl.md

@@ -39,6 +39,7 @@ The following special commands are supported by all REPL instances:
   further input or processing of that expression.
 * `.clear`: Resets the REPL `context` to an empty object and clears any
   multi-line expression being input.
+* `.cls`: Clear the screen (or press <kbd>Ctrl</kbd>+<kbd>L</kbd>).
 * `.exit`: Close the I/O stream, causing the REPL to exit.
 * `.help`: Show this list of special commands.
 * `.save`: Save the current REPL session to a file:

lib/repl.js

@@ -191,6 +191,11 @@ const {
 const {
   makeContextifyScript,
 } = require('internal/vm');
+const {
+  clearScreenDown,
+  cursorTo,
+} = require('internal/readline/callbacks');
+
 let nextREPLResourceNumber = 1;
 // This prevents v8 code cache from getting confused and using a different
 // cache from a resource of the same name
@@ -1836,6 +1841,16 @@ function defineDefaultCommands(repl) {
       this.displayPrompt();
     },
   });
+
+  repl.defineCommand('cls', {
+    help: 'Clear the screen',
+    action: function() {
+      cursorTo(this.output, 0, 0);
+      clearScreenDown(this.output);
+      this.displayPrompt();
+    },
+  });
+
   if (repl.terminal) {
     repl.defineCommand('editor', {
       help: 'Enter editor mode',

test/parallel/test-repl-cls-command.js

@@ -0,0 +1,22 @@
+'use strict';
+
+require('../common');
+const assert = require('assert');
+const repl = require('repl');
+const ArrayStream = require('../common/arraystream');
+
+// eslint-disable-next-line no-control-regex
+const clearChar = /\[1;1H\u001b\[0J>/;
+let accum = '';
+const output = new ArrayStream();
+output.write = (data) => (accum += data.replace('\r', ''));
+
+const r = repl.start({
+  input: new ArrayStream(),
+  output,
+});
+['new Error', 'Promise'].forEach((cmd) => r.write(`${cmd}\n`));
+assert.strictEqual(accum.match(clearChar), null);
+r.write('.cls\n');
+assert.strictEqual(accum.match(clearChar).length > 0, true);
+r.write('.exit\n');

test/parallel/test-repl.js

@@ -458,6 +458,7 @@ const errorTests = [
     expect: [
       /\.break/,
       /\.clear/,
+      /\.cls/,
       /\.exit/,
       /\.help/,
       /\.load/,