These are what I learned in 2018-01-08.

Author: khanhicetea

README.md

@@ -13,11 +13,11 @@ This repo has a tool that help you to manage and write down what you learned in
 | Table of Contents | :point_down: |
 | -------- | -------- |
 | :new: **Top 5 recent learning** | |
+| [Debug js code using console.trace](javascript/Debug-js-code-using-console.trace.md) [javascript] | 2018-01-07 |
+| [Define property of an object in hacking way](javascript/Define-property-of-an-object-in-hacking-way.md) [javascript] | 2018-01-07 |
 | [Sleeping connections in MySQL](mysql/Sleeping-connections-in-MySQL.md) [mysql] | 2018-01-04 |
 | [Create cross-platform downloading app URL](http/Create-crossplatform-downloading-app-URL.md) [http] | 2018-01-03 |
 | [HSTS rule in browser](web/HSTS-rule-in-browser.md) [web] | 2018-01-03 |
-| [Using web proxy to bypass firewalls](web/Using-web-proxy-to-bypass-firewalls.md) [web] | 2017-12-07 |
-| [Fastly conflict detector script](git/Fastly-conflict-detector-script.md) [git] | 2017-11-27 |
 | :books: **bash** [ 1 articles ] | |
 | [Simple HTTP server function helper](bash/simple-http-server-function-helper.md) | 2017-10-05 |
 | :books: **chrome-dev** [ 1 articles ] | |
@@ -42,9 +42,11 @@ This repo has a tool that help you to manage and write down what you learned in
 | [Create cross-platform downloading app URL](http/Create-crossplatform-downloading-app-URL.md) | 2018-01-03 |
 | :books: **java** [ 1 articles ] | |
 | [Runing old java applets on brower](java/Runing-old-java-applets-on-brower.md) | 2017-08-06 |
-| :books: **javascript** [ 2 articles ] | |
+| :books: **javascript** [ 4 articles ] | |
 | [Eval function and with block](javascript/Eval-function-and-with-block.md) | 2017-08-10 |
 | [Scope and Closure](javascript/Scope-and-Closure.md) | 2017-08-10 |
+| [Debug js code using console.trace](javascript/Debug-js-code-using-console.trace.md) | 2018-01-07 |
+| [Define property of an object in hacking way](javascript/Define-property-of-an-object-in-hacking-way.md) | 2018-01-07 |
 | :books: **linux** [ 3 articles ] | |
 | [Remap Capslock to Control key](linux/remap-capslock-to-control-key.md) | 2017-08-08 |
 | [Send ENTER key to kernel](linux/Send-ENTER-key-to-kernel.md) | 2017-09-27 |

javascript/Debug-js-code-using-console.trace.md

@@ -0,0 +1,24 @@
+- Date : 2018-01-07
+- Tags : #javascript #debug
+
+## Debug js code using console.trace
+
+Browsers provide an useful function help you debug easier than using simple `console.log` function.
+
+That is `console.trace`, which prints a stack trace to called function.
+
+Example :
+
+```js
+function foo() {
+	var a = 1;
+	bar(a);
+}
+function bar(x) {
+	console.log(x);
+	console.trace();
+}
+
+foo();
+```
+

javascript/Define-property-of-an-object-in-hacking-way.md

@@ -0,0 +1,40 @@
+- Date : 2018-01-07
+- Tags : #javascript
+
+## Define property of an object in hacking way
+
+Sometimes, we want to define a property of an advanced object (has setter and getter function).
+
+Now, we could use this helper function `Object.defineProperty` to define property of an object in a cool way.
+
+Example :
+
+```js
+const foo = {};
+
+Object.defineProperty(a, 'bar', {
+	value: 'hogehoge',
+	writable: false,
+});
+
+console.log(foo.bar); // 'hogehoge'
+foo.bar = 'foo bar'; // throw an error in strict mode
+console.log(foo.bar); // still be 'hogehoge'
+```
+
+Modifying setter, getter function
+
+```js
+// Get callstack which function is getting or setting cookie value
+Object.defineProperty(document, 'cookie', {
+	get: function() {
+		console.log('get !');
+		console.trace();
+	},
+	set: function(val) {
+		console.log('set = ', val);
+		console.trace();
+	},
+}); 
+```
+