add tip basics declarations

README.md

@@ -30,6 +30,7 @@ There are a lot of ways to get update, choose your own
 
 # Tips list
 
+- 47 - [Basics : declarations](https://github.com/loverajoel/jstips/blob/gh-pages/_posts/en/2016-02-15-basics-declarations.md)
 - 46 - [Detect document ready in pure JS](https://github.com/loverajoel/jstips/blob/gh-pages/_posts/en/2016-02-15-detect-document-ready-in-pure-js.md)
 - 45 - [Calculate the Max/Min value from an array](https://github.com/loverajoel/jstips/blob/gh-pages/_posts/en/2016-02-14-calculate-the-max-min-value-from-an-array.md)
 - 44 - [Know the passing mechanism](https://github.com/loverajoel/jstips/blob/gh-pages/_posts/en/2016-02-13-know-the-passing-mechanism.md)

_posts/en/2016-02-15-basics-declarations.md

@@ -0,0 +1,62 @@
+---
+layout: post
+
+title: Basics declarations
+tip-number: 47
+tip-username: adaniloff 
+tip-username-profile: https://github.com/adaniloff
+tip-tldr: Understand and work with declarations.
+
+categories:
+    - en
+---
+
+Below, different ways to declare variables in javascript.
+Comments and console.log should be enough to explain what's happening here:
+
+```js
+var y, x = y = 1 //== var x; var y; x = y = 1
+console.log('--> 1:', `x = ${x}, y = ${y}`)
+
+// Will print
+//--> 1: x = 1, y = 1
+
+;(() => { 
+  var x = y = 2 // == var x; y = 2;
+  console.log('2.0:', `x = ${x}, y = ${y}`)
+})()
+console.log('--> 2.1:', `x = ${x}, y = ${y}`)
+
+// Will print
+//2.0: x = 2, y = 2
+//--> 2.1: x = 1, y = 2
+
+;(() => { 
+  var x, y = 3 // == var x; var y = 3;
+  console.log('3.0:', `x = ${x}, y = ${y}`)
+})()
+console.log('--> 3.1:', `x = ${x}, y = ${y}`)
+
+// Will print
+//3.0: x = undefined, y = 3
+//--> 3.1: x = 1, y = 2
+
+;(() => { 
+  var y, x = y = 4 // == var x; var y; x = y = 3
+  console.log('4.0:', `x = ${x}, y = ${y}`)
+})()
+console.log('--> 4.1:', `x = ${x}, y = ${y}`)
+
+// Will print
+//4.0: x = 4, y = 4
+//--> 4.1: x = 1, y = 2
+
+x = 5 // == x = 5
+console.log('--> 5:', `x = ${x}, y = ${y}`)
+
+// Will print
+//--> 5: x = 5, y = 2
+```
+
+More informations available on the [MDN](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Statements/var).
+