Tutorial by Examples: ev

Access Levels

Ruby has three access levels. They are public, private and protected. Methods that follow the private or protected keywords are defined as such. Methods that come before these are implicitly public methods. Public Methods A public method should describe the behavior of the object being created. T...

Ruby Language • Classes

Retrieving data from a file

The following snippet opens a JSON encoded file (replace filename with the actual name of the file) and returns the object that is stored in the file. import json with open(filename, 'r') as f: d = json.load(f)

Python Language • JSON Module

Basic PDO Connection and Retrieval

Since PHP 5.0, PDO has been available as a database access layer. It is database agnostic, and so the following connection example code should work for any of its supported databases simply by changing the DSN. // First, create the database handle //Using MySQL (connection via local socket): $d...

PHP • PDO

Removing event listeners

The removeEventListener() method removes event handlers that have been attached with the addEventListener() method: element.removeEventListener("mousemove", myFunction); Everything (eventname, function, and options) in the removeEventListener must match the one set when adding the even...

DOM • Events

Reversing an object

You can use slices to very easily reverse a str, list, or tuple (or basically any collection object that implements slicing with the step parameter). Here is an example of reversing a string, although this applies equally to the other types listed above: s = 'reverse me!' s[::-1] # '!em esrever...

Python Language • Indexing and Slicing

Use multiple versions of Xcode

You can have multiple versions of Xcode installed at the same time (including beta versions). Simply rename the application in Finder to avoid conflicts. Note: Installing Xcode from the App Store will tend to overwrite an existing version on your machine. You can also install Xcode from a direct ...

Xcode • Getting started with Xcode

Comparing Date values

To check the equality of Date values: var date1 = new Date(); var date2 = new Date(date1.valueOf() + 10); console.log(date1.valueOf() === date2.valueOf()); Sample output: false Note that you must use valueOf() or getTime() to compare the values of Date objects because the equality operato...

JavaScript • Date Comparison

Event Object

To access the event object, include an event parameter in the event listener callback function: var foo = document.getElementById("foo"); foo.addEventListener("click", onClick); function onClick(event) { // the `event` parameter is the event object // e.g. `event.type`...

DOM • Events

Exported vs. Unexported Fields (Private vs Public)

Struct fields whose names begin with an uppercase letter are exported. All other names are unexported. type Account struct { UserID int // exported accessToken string // unexported } Unexported fields can only be accessed by code within the same package. As such, if you are ev...

Go • Structs

Event Bubbling and Capturing

Events fired on DOM elements don't just affect the element they're targeting. Any of the target's ancestors in the DOM may also have a chance to react to the event. Consider the following document: <!DOCTYPE html> <html> <head> <meta charset="utf-8" /> </hea...

DOM • Events

Downloading a file via curl

This downloads a file from the Dropbox API at the remote path /Homework/math/Prime_Numbers.txt to the local path Prime_Numbers.txt in the current folder: curl -X POST https://content.dropboxapi.com/2/files/download \ --header "Authorization: Bearer <ACCESS_TOKEN>" \ --head...

Dropbox API • Downloading a file

Downloading a file with every error case handled using the SwiftyDropbox library

Dropbox.authorizedClient!.files.download(path: path, destination: destination).response { response, error in if let (metadata, url) = response { print("*** Download file ***") print("Downloaded file name: \(metadata.name)") print("Downloaded f...

Dropbox API • Downloading a file

Downloading a file via curl in C++

#include <stdio.h> #include <curl/curl.h> int main (int argc, char *argv[]) { CURL *curl; CURLcode res; /* In windows, this will init the winsock stuff */ curl_global_init(CURL_GLOBAL_ALL); /* get a curl handle */ curl = curl_easy_init()...

Dropbox API • Downloading a file

Downloading a piece of a file via curl using Range Retrieval Requests

This downloads just a piece of a file, using Range Retrieval Requests, from the Dropbox API at the remote path /Homework/math/Prime_Numbers.txt to the local path Prime_Numbers.txt.partial in the current folder: curl -X GET https://content.dropboxapi.com/2/files/download \ --header "Auth...

Dropbox API • Downloading a file

Uploading a file via curl in PHP

<?php $path = 'test_php_upload.txt'; $fp = fopen($path, 'rb'); $size = filesize($path); $cheaders = array('Authorization: Bearer <ACCESS_TOKEN>', 'Content-Type: application/octet-stream', 'Dropbox-API-Arg: {"path":"/test/'.$path.'...