diff --git a/1-js/01-getting-started/3-devtools/article.md b/1-js/01-getting-started/3-devtools/article.md
index 14c9c390..442236e7 100644
--- a/1-js/01-getting-started/3-devtools/article.md
+++ b/1-js/01-getting-started/3-devtools/article.md
@@ -50,6 +50,12 @@ Open Preferences and go to the "Advanced" pane. There's a checkbox at the bottom
 
 Now `key:Cmd+Opt+C` can toggle the console. Also, note that the new top menu item named "Develop" has appeared. It has many commands and options.
 
+## Multi-line input
+
+Usually, when we put a line of code into the console, and then press `ley:Enter`, it executes.
+
+To insert multiple line, press `key:Shift+Enter`.
+
 ## Summary
 
 - Developer tools allow us to see errors, run commands, examine variables, and much more.
diff --git a/1-js/02-first-steps/03-strict-mode/article.md b/1-js/02-first-steps/03-strict-mode/article.md
index bd6a54f0..ff6c1527 100644
--- a/1-js/02-first-steps/03-strict-mode/article.md
+++ b/1-js/02-first-steps/03-strict-mode/article.md
@@ -47,6 +47,24 @@ There is no directive like `"no use strict"` that reverts the engine to old beha
 Once we enter strict mode, there's no return.
 ```
 
+## Browser console
+
+For the future, when you use a browser console to test features, please note that it doesn't `use strict` by default.
+
+Sometimes, when `use strict` makes a difference, you'll get incorrect results.
+
+Even if we press `key:Shift+Enter` to input multiple lines, and put `use strict` on top, it doesn't work. That's because of how the console executes the code internally.
+
+The reliable way to ensure `use strict` would be to input the code into console like this:
+
+```
+(function() {
+  'use strict';
+
+  // ...your code...
+})()
+```
+
 ## Always "use strict"
 
 We have yet to cover the differences between strict mode and the "default" mode.
diff --git a/1-js/11-async/08-async-iteration-generators/article.md b/1-js/11-async/08-async-iteration-generators/article.md
index 743f5706..e92dc8bb 100644
--- a/1-js/11-async/08-async-iteration-generators/article.md
+++ b/1-js/11-async/08-async-iteration-generators/article.md
@@ -41,7 +41,7 @@ let range = {
   }
 };
 
-for(let value in range) {
+for(let value of range) {
   alert(value); // 1 then 2, then 3, then 4, then 5
 }
 ```