GideonBabu

System Design Cheatsheet

Picking the right architecture = Picking the right battles + Managing trade-offs

Basic Steps

1. Clarify and agree on the scope of the system

• User cases (description of sequences of events that, taken together, lead to a system doing something useful)
  • Who is going to use it?
  • How are they going to use it?

GideonBabu

# Terminal Cheat Sheet

pwd         # print working directory
ls          # list files in directory
cd          # change directory
~           # home directory
..          # up one directory
-           # previous working directory
help        # get help
-h          # get help

GideonBabu

JavaScript variable naming:
1. Names can contain letters, digits, underscores, and dollar signs.
2. Names must begin with a letter
3. Names can also begin with $ and _ (but we will not use it in this tutorial)
4. Names are case sensitive (y and Y are different variables)
5. Reserved words (like JavaScript keywords) cannot be used as names

GideonBabu

// to revert a file
svn revert filename

// to revert all the files inside folder named [htdocs]
// http://svnbook.red-bean.com/en/1.8/svn.ref.svn.c.revert.html
cd htdocs
svn revert -R .

GideonBabu

You can compare two table structures and see the differences in columns, keys, indexes, and other structural table elements. In the Database tool window (View | Tool Windows | Database), select two tables. Right-click the selection and navigate to Compare Ctrl+D.
To compare contents of two tables, right-click two tables and navigate to Compare Content.

+++

You can add a brief description of any breakpoint to ease search in future.
Press Ctrl+Shift+8 to view all existing breakpoints, then right-click the breakpoint you want to provide a description for, and choose Edit description

+++

GideonBabu

[abc] A single character: a, b or c
[^abc] Any single character but a, b, or c
[a-z] Any single character in the range a-z
[a-zA-Z] Any single character in the range a-z or A-Z
^ Start of line
$ End of line
\A Start of string
\z End of string
. Any single character
\s Any whitespace character

GideonBabu

/*
This is from
http://uihacker.blogspot.com/2011/04/javascript-handle-touch-gestures-for.html

I wrote a little class to handle pinch & rotate gestures on a web page in iOS. There's a bunch of event listener adding/removing, which can get a little messy, so this should help keep your code clean if you need to handle gestures.

Here's the class:
*/

function GestureCallback( element, endCallback, changeCallback ) {

GideonBabu

// detect the Enter key in a text input field

$(".input1").on('keyup', function (e) {
    if (e.keyCode === 13) {
        // Do something
    }
});

// array for..of cycle
// tip: you can stop iterating at any time using a break statement.

GideonBabu

/*
 * disable auto-zoom on iphone input field focus 
 * http://www.456bereastreet.com/archive/201212/ios_webkit_browsers_and_auto-zooming_form_controls/
*/
input[type='text']:focus,
input[type='number']:focus,
textarea:focus {
	font-size: 16px;
}

GideonBabu

Better performance - PHP 7 is twice as fast as PHP 5.6. Optimization 

Scalar type declarations - pass function params with variable type

function sum (int $a, int $b){
	
}
Return type declarations - mention the return variable type of a function

function sum ($a, $b): int{