Tutorial by Examples: an

jQuery datepicker has two options to allow displaying dropdowns for month and year selection. These options make navigation through large timeframes easier. <input type="text" id="datepicker"> <script> $("#datepicker").datepicker({ changeMont...

class AnimatedImage extends Component { constructor(props){ super(props) this.state = { logoMarginTop: new Animated.Value(200) } } componentDidMount(){ Animated.timing( this.state.logoMarginTop, { toValue: 100 ...

<style> input:in-range { border: 1px solid blue; } </style> <input type="number" min="10" max="20" value="15"> <p>The border for this value will be blue</p> The :in-range CSS pseudo-class matches when an element...

All we need to do is to use set() method of $query object. It takes two arguments, first what we want to set and second what value to set. add_action( 'pre_get_posts', 'change_posts_per_page' ); function change_posts_per_page( $query ) { if( !$query->is_main_query() || is_admin() ) retu...

Let's say you need to check if an email address appears in a long list of email addresses. Use the MATCH function to return the row number on which the email address can be found. If there is no match, the function returns an #N/A error. =MATCH(F2,$D$2:$D$200,0) The value you're retrieving ...

This will rollback both inserts due to an invalid datetime: BEGIN TRANSACTION BEGIN TRY INSERT INTO dbo.Sale(Price, SaleDate, Quantity) VALUES (5.2, GETDATE(), 1) INSERT INTO dbo.Sale(Price, SaleDate, Quantity) VALUES (5.2, 'not a date', 1) COMMIT TRANSACTION END TRY BEG...

The Math.max() function returns the largest of zero or more numbers. Math.max(4, 12); // 12 Math.max(-1, -15); // -1 The Math.min() function returns the smallest of zero or more numbers. Math.min(4, 12); // 4 Math.min(-1, -15); // -15 Getting maximum and minimum from an array: var ...

To use the constant simply use its name: if (EARTH_IS_FLAT) { print "Earth is flat"; } print APP_ENV_UPPERCASE; or if you don't know the name of the constant in advance, use the constant function: // this code is equivalent to the above code $const1 = "EARTH_IS_FLAT&quo...

Let's say we have type ENUM('fish','mammal','bird') An alternative is type TINYINT UNSIGNED plus CREATE TABLE AnimalTypes ( type TINYINT UNSIGNED NOT NULL AUTO_INCREMENT, name VARCHAR(20) NOT NULL COMMENT "('fish','mammal','bird')", PRIMARY KEY(type), INDEX(na...

Let's say we have type ENUM('fish','mammal','bird') An alternative is type VARCHAR(20) COMENT "fish, bird, etc" This is quite open-ended in that new types are trivially added. Comparison, and whether better or worse than ENUM: (same) INSERT: simply provide the string (worse?)...

ALTER TABLE tbl MODIFY COLUMN type ENUM('fish','mammal','bird','insect'); Notes As with all cases of MODIFY COLUMN, you must include NOT NULL, and any other qualifiers that originally existed, else they will be lost. If you add to the end of the list and the list is under 256 items, the ALTER...

Changing an auto-increment value is useful when you don't want a gap in an AUTO_INCREMENT column after a massive deletion. For example, you got a lot of unwanted (advertisement) rows posted in your table, you deleted them, and you want to fix the gap in auto-increment values. Assume the MAX value o...

attr() gets/sets the HTML attribute using the DOM functions getAttribute() and setAttribute(). prop() works by setting the DOM property without changing the attribute. In many cases the two are interchangeable, but occasionally one is needed over the other. To set a checkbox as checked: $('#tosAcc...

$q is a built-in service which helps in executing asynchronous functions and using their return values(or exception) when they are finished with processing. $q is integrated with the $rootScope.Scope model observation mechanism, which means faster propagation of resolution or rejection into your m...

The angular.identity function returns the first argument passed to it. angular.identity(argument) This function is useful for functional programming, you can provide this function as a default in case an expected function was not passed. Examples: angular.identity(42) // 42 var mutate = f...

The angular.forEach accepts an object and an iterator function. It then runs the iterator function over each enumerable property/value of the object. This function also works on arrays. Like the JS version of Array.prototype.forEach The function does not iterate over inherited properties (prototype...

ALTER TABLE fish_data.fish DROP PRIMARY KEY; ALTER TABLE fish_data.fish MODIFY COLUMN fish_id DECIMAL(20,0) NOT NULL PRIMARY KEY; An attempt to modify the type of this column without first dropping the primary key would result in an error.

Sometimes it's useful to be able to extend a class with new functions. For example let's suppose that a string should be converted to a camel case string. So we need to tell TypeScript, that String contains a function called toCamelCase, which returns a string. interface String { toCamelCase()...

Standard properties Depending on the type of the property, there are up to 3 methods for a single property. Let <property> denote the name of a property and <Property> the name of the property with an uppercase first letter. And let T be the type of the property; for primitive wrappers ...

# list gem sources: gem sources -l # remove default gem source: gem sources -r https://rubygems.org/ # add other gem sources: gem sources -a https://ruby.taobao.org/