JavaScript for PHP Developers

JavaScript for PHP developers The Good Parts Karsten Dambekalns <karsten@typo3.org> Freitag, 15. Mai 2009

What this is about the JavaScript language not DOM not browsers not JS frameworks not website building Freitag, 15. Mai 2009

Am I qualiﬁed? Probably not, when it comes to JS Absolutely when it comes to PHP Freitag, 15. Mai 2009

My JS background First JS usage in the days of NN4 Used DynAPI, modiﬁed it Saw alert() ﬁx timing issues in browsers Was happy when I did not have to use JavaScript anymore Thought I would never touch it again Freitag, 15. Mai 2009

In JavaScript, there is a beautiful, elegant, highly expressive language... Freitag, 15. Mai 2009

...that is buried under a steaming pile of good intentions and blunders. Douglas Crockford Freitag, 15. Mai 2009

Grammar Freitag, 15. Mai 2009

Names Names can be chosen freely Some words are reserved, most of them not used in JavaScript, though Some word should have been reserved: NaN, Inﬁnity, undeﬁned Freitag, 15. Mai 2009

Numbers Only one type, 64 bit ﬂoating point internally Numbers have methods (Most things in JavaScript are objects) Freitag, 15. Mai 2009

Strings 16 bit Unicode, as such somewhat limited Strings have methods and properties toUpperCase(), length Concatenation is done with +, as is addition (Beware of errors as a result of this!) Freitag, 15. Mai 2009

var Most confusing for me was var – it seemed to make no difference most of the time Inside a function var deﬁnes a function’s private variables Otherwise variables will be globally accessible! Freitag, 15. Mai 2009

Type issues typeof returns a string with a type For arrays and null it returns ‘object’ typeof NaN === ‘number’ // true! undeﬁned and NaN are global variables – you can change their values Freitag, 15. Mai 2009

Functions Freitag, 15. Mai 2009

Basics Functions are objects, they can be stored in variables, arrays, objects passed as arguments and returned Functions can have methods (they are objects!) Freitag, 15. Mai 2009

Deﬁning functions JavaScript has a function statement and a function expression: function foo() {} means about the same as var foo = function foo() {} Remember: functions are values Freitag, 15. Mai 2009

Closure Inner functions can access parameters and variables of the context in which they are created This can be used to protect variables against manipulation to keep values over function calls Freitag, 15. Mai 2009

var myObject = function () { var value = 0; return { increment: function (inc) { value += typeof inc === ‘number ? inc : 1; } getValue: function () { return value; } }(); Freitag, 15. Mai 2009

Objects Freitag, 15. Mai 2009

Basics Numbers, strings, booleans, null, undeﬁned are simple types Everything else is an object: arrays, functions, regular expressions Objects have properties with name and value Objects are class free Freitag, 15. Mai 2009

Object literals Very cool way of creating objects, confusing if seen for the ﬁrst time (no new?!) var ﬂight = { airline: ‘FLOW Flights’, number: 3, captain: { ... } } Freitag, 15. Mai 2009

The new statement new creates an object that inherits from the operand, then calls the operand with the created object bound to this If the operand customizes the object but you forgot new, you change global variables! If you use new, make constructor method names UpperCamelCase Freitag, 15. Mai 2009

Inheritance Objects inherit from objects, no classes Prototypal inheritence allows to augment existing objects during runtime: Foo.prototype.bar = function () { ... } Even built-in objects can be enhanced Local properties hide inherited ones Freitag, 15. Mai 2009

Arrays Freitag, 15. Mai 2009

Basics Arrays can be created with array literals: var data = [‘one’, ‘two’, ‘three’]; The length property of an array is the largest integer property name +1 can be set and thus cut off arrays at the end Freitag, 15. Mai 2009

Array or Object? Simple rule for what to use: When property names are small sequential integers, use an array. Otherwise an object. Hard to ﬁnd out what you have: You need to deﬁne a useful is_array method yourself. Freitag, 15. Mai 2009

Awful & bad parts Freitag, 15. Mai 2009

Semicolon inerstion JavaScript tries to ﬁx programs by inserting semicolons – do not rely on that! What does this return? return { status: true }; Freitag, 15. Mai 2009

parseInt parseInt(’16’) == parseInt(’16 tons’) == 16 parseInt(’08’) returns 0 because it assumes octal numbers Always provide the radix parameter to parseInt Freitag, 15. Mai 2009

Bitwise operators Avoid them if you think you gain speed All numbers are ﬂoating point, so bitwise operators convert to integer and back Freitag, 15. Mai 2009

Read this! JavaScript: The Good Parts Douglas Crockford O’Reilly Freitag, 15. Mai 2009

Thanks! Freitag, 15. Mai 2009

JavaScript for PHP Developers

by Karsten Dambekalns on May 15, 2009

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JavaScript for PHP Developers — Presentation Transcript