Onclick event in JavaScript

The onclick event occurs when an object gets clicked.

Syntax

onclick="SomeJavaScriptCode" 

Parameter: SomeJavaScriptCode
Description: Required. Specifies a JavaScript to be executed when the event occurs.

Example
In this example the text in the first input field will be copied to the second input field when a button is clicked:
<!DOCTYPE html><html><head><title>Online HTML Editor - webspeckle.com</title></head><body><h3>Onclick event in JavaScript:</h3>Field1: <input type="text" id="field1" value="Hello World!"><br />Field2: <input type="text" id="field2"><br /><br />Click the button below to copy the content of Field1 to Field2. <br /><button onclick="document.getElementById('field2').value= document.getElementById('field1').value">Copy Text</button></body></html>
Demo

Encode a set of form elements as a string for submission

The .serialize() method creates a text string in standard URL-encoded notation. It operates on a jQuery object representing a set of form elements.

.serialize( )

Eg:

<form>
  <div><input type="text" name="a" value="1" id="a" /></div>
  <div><input type="text" name="b" value="2" id="b" /></div>
  <div><input type="hidden" name="c" value="3" id="c" /></div>
  <div>
    <textarea name="d" rows="8" cols="40">4</textarea>
  </div>
  <div><select name="e">
    <option value="5" selected="selected">5</option>
    <option value="6">6</option>
    <option value="7">7</option>
  </select></div>
  <div>
    <input type="checkbox" name="f" value="8" id="f" />
  </div>
  <div>
    <input type="submit" name="g" value="Submit" id="g" />
  </div>
</form>

The .serialize() method can act on a jQuery object that has selected individual form elements, such as <input>, <textarea>, and <select>. However, it is typically easier to select the <form> tag itself for serialization:

$('form').submit(function()
{
  alert($(this).serialize());
  return false;
});

This produces a standard-looking query string:

a=1&b=2&c=3&d=4&e=5

Warning: selecting both the form and its children will cause duplicates in the serialized string.

Note: Only "successful controls" are serialized to the string. No submit button value is serialized since the form was not submitted using a button. For a form element's value to be included in the serialized string, the element must have a name attribute. Values from checkboxes and radio buttons (inputs of type "radio" or "checkbox") are included only if they are checked. Data from file select elements is not serialized.

Final code and demo is here
<!DOCTYPE html><html><head><title>Online HTML Editor - webspeckle.com</title><script src="https://ajax.googleapis.com/ajax/libs/jquery/3.2.1/jquery.min.js"></script><style> </style><script>$(document).ready(function () { $('form').submit(function() { alert($(this).serialize()); return false; }); }); </script></head><body><h3>Encode a set of form elements as a string for submission:</h3><form> <div><input type="text" name="a" value="1" id="a" /></div><div><input type="text" name="b" value="2" id="b" /></div><div><input type="hidden" name="c" value="3" id="c" /></div><div><select name="e"> <option selected="selected" value="5">5</option> <option value="6">6</option> <option value="7">7</option> </select></div><div><input id="f" name="f" type="checkbox" value="8" /> </div><div><input id="g" name="g" type="submit" value="Submit" /> </div>
Demo

What is gulp.js?

gulp is a toolkit that helps you automate painful or time-consuming tasks in your development workflow. It is a task runner built on Node.js and npm, used for automation of time-consuming and repetitive tasks involved in web development like minification, concatenation, cache busting, unit testing, linting, optimization etc.

Getting Started

1) Install 'nodejs'
2) Create 'package.json'
3) Create 'gulpfile.js'
4) run 'gulp' command

Install 'nodejs'

After installing go to the project directory through 'Node.js command prompt' and check the version first

node --version
npm --version

Install the gulp command

npm install --global gulp-cli

Create a package.json

npm init

If you don't have a package.json, create one. If you need help, run an 'npm init' which will walk you through giving it a name, version, description, etc.
A sample file look like this

{
  "name": "PROJECT_NAME",
  "version": "PROJECT_VERSION",
  "description": "PROJECT_DESCRIPTION",
  "main": "",
  "dependencies": {
    "gulp": "^3.9.1"
  },
  "devDependencies": {
    "del": "^3.0.0",
    "gulp": "^3.9.1",
    "gulp-concat": "^2.6.1",
    "gulp-uglify": "^3.0.0",
  },
  "scripts": {
    "test": "echo \"Error: no test specified\" && exit 1"
  },
  "author": "AUTHOR",
  "license": "ISC"
}

Install gulp in your devDependencies

npm install --save-dev gulp

Create a gulpfile

In your project directory, create a file named gulpfile.js in your project root.
A sample file look like this

var gulp = require('gulp');
var concat = require('gulp-concat');
var uglify = require('gulp-uglify');
var del = require('del');
var paths = {
  scripts: ['client/js/**/*.js']
};

gulp.task('clean', function() {
  return del(['build']);
});
gulp.task('scripts', ['clean'], function() {
  // Minify and copy all JavaScript (except vendor scripts)
  return gulp.src(paths.scripts)
      .pipe(uglify())
      .pipe(concat('all.min.js'))
    .pipe(gulp.dest('build/js'));
});

gulp.task('default', ['scripts']);

Run gulp

gulp

run 'gulp' command in 'Node.js command prompt'

After run gulp command all your 'js' files minimized and compressed to a single file 'all.min.js.' A folder 'build' will create in your project directory. It has another folder 'js'. This 'js' folder contains a single js file 'all.min.js'.

Free file and folder comparison tool for developers

Meld is a visual diff and merge tool targeted at developers. Meld helps you compare files, directories, and version controlled projects. It provides two- and three-way comparison of both files and directories.

Meld is packaged for most Linux/Unix distributions, including Fedora, Ubuntu, and Suse. Unless you want the absolutely latest version, you should install Meld through your package manager.

Features
Two- and three-way comparison of files and directories
File comparisons update as you type
Auto-merge mode and actions on change blocks help make merges easier
Visualisations make it easier to compare your files
Supports Git, Bazaar, Mercurial, Subversion, etc.

Visit: http://meldmerge.org/

Meld is licensed under the GPL v2, except as noted. 

Is Qt supports JSON?

YES. Qt provides support for dealing with JSON data. JSON is a format to encode object data derived from Javascript, but now widely used as a data exchange format on the internet. The JSON support in Qt provides an easy to use C++ API to parse, modify and save JSON data. It also contains support for saving this data in a binary format that is directly "mmap"-able and very fast to access.

JSON is a format to store structured data. It has 6 basic data types:

bool, double, string, array, object, null

The text representation of JSON encloses arrays in square brackets ([ ... ]) and objects in curly brackets ({ ... }). Entries in arrays and objects are separated by commas. The separator between keys and values in an object is a colon (:).

A simple JSON document encoding a person, his/her age, address and phone numbers could look like:

{
    "FirstName": "John",
    "LastName": "Doe",
    "Age": 43,
    "Address": {
        "Street": "Downing Street 10",
        "City": "London",
        "Country": "Great Britain"
    },
    "Phone numbers": [
        "+44 1234567",
        "+44 2345678"
    ]
}

JSON support in Qt consists of these classes:

QJsonArray	Encapsulates a JSON array
QJsonDocument	Way to read and write JSON documents
QJsonParseError	Used to report errors during JSON parsing
QJsonObject	Encapsulates a JSON object
QJsonObject::const_iterator	QJsonObject::const_iterator class provides an STL-style const iterator for QJsonObject
QJsonObject::iterator	QJsonObject::iterator class provides an STL-style non-const iterator for QJsonObject
QJsonValue	Encapsulates a value in JSON

Which are the supported databases in qt?

Qt5 supports SQLite, MySQL, DB2, Borland InterBase, Oracle, ODBC, and PostgreSQL.

The table below lists the drivers included with Qt. Due to license incompatibilities with the GPL, not all of the plugins are provided with Open Source Versions of Qt.

Driver name	DBMS
QDB2	IBM DB2 (version 7.1 and above)
QIBASE	Borland InterBase
QMYSQL	MySQL
QOCI	Oracle Call Interface Driver
QODBC	Open Database Connectivity (ODBC) - Microsoft SQL Server and other ODBC-compliant databases
QPSQL	PostgreSQL (versions 7.3 and above)
QSQLITE2	SQLite version 2
QSQLITE	SQLite version 3
QTDS	Sybase Adaptive Server Note: obsolete from Qt 4.7

How to check if a value is not a number in JavaScript?

The isNaN() function is used to check if a value is not a number.

Syntax

isNaN(number) 

Parameter: number Required.
Description: The value to be tested

Example
In this example we use isNaN() to check some values:

<script type="text/javascript">
document.write(isNaN(123)+ "<br />");
document.write(isNaN(-1.23)+ "<br />");
document.write(isNaN(5-2)+ "<br />");
document.write(isNaN(0)+ "<br />");
document.write(isNaN("Hello")+ "<br />");
document.write(isNaN("2005/12/12")+ "<br />");
</script>

The output of the code above will be:
false
false
false
false
true
true

Final code and demo is here
<!DOCTYPE html><html><head><title>Online HTML Editor - webspeckle.com</title></head><body><h3>How to check if a value is not a number in JavaScript?</h3><script type="text/javascript">document.write(isNaN(123)+ "<br />"); document.write(isNaN(-1.23)+ "<br />"); document.write(isNaN(5-2)+ "<br />"); document.write(isNaN(0)+ "<br />"); document.write(isNaN("Hello")+ "<br />"); document.write(isNaN("2005/12/12")+ "<br />"); </script></body></html>
Demo