javascript definitive guide

variable = = "undefined") {Do something;}Bad writing: The use of undefined direct volumeif (variable = = undefined) {Do something;}Four: operator spacingA space must be used before and after the ternary operator to keep the expression neat.Operators include assignment operators and logical operatorsGood wording.var found = (Value[i] = = = False);Good wording.if (found (Count > 10)) {DoSomething ();}Good wording.for (i = 0; i Process (i);}Bad wording: Lost spacevar found = (varlues[i]===false);

1. JavaScript is case sensitive, but HTML is not case sensitive2, JS will ignore the space between the logo, in most cases will also ignore the newline character, so to useNeat, Consistent coding style3,//As the end of the comment,/* and/* can be used as a cross-line comment, but cannot have nested noteRelease4. The identifier must start with a letter, underscore, or dollar sign (the number is not allowed as the first wordcharacter), subsequent charac

1. For ... in ... The ApplicationExample: var obj = {x:3,y: ' Apple ', Z: ' Good ', w:0.95};var emptyobj = [],i = 0;For (p in obj) {emptyobj[i++] = obj[p];};Alert (emptyobj[2]);2. Jump A. Break and continue can represent target loops or other statementsB. Return jumps out of the function body and provides the result of this callC. Throw triggers or throws an exception3. Label statements For example: Mainloop:while (!x) {TodoContinue Mainloop;Todo}4. Throw201506051031_ "

1.To avoid such circular reference problems, it is best to manually break the connection between the native JS object and the DOM element when you do not use them:Code:myobject.element = NULL;ELEMENT.O = null;2. Isfinite (); is a finite number3. Lenin's understanding of the logical approach: A. Hold and study all aspects , contacts and intermediaries of things. Observe things in the development, movement, and change of things. C. Define all human practices into the "definition" of thing

I. Constructor call (with or without return)1. var obj = new Object ();var obj = new Object;The two lines of code are equivalent; expression: New obj.m ();, this is not obj!! The constructor is usually not used with the return keyword;Two. Indirect calls1. Call (), and apply (); Function: Any object can call any method/Call ();--use its own arguments as arguments to the function;Apply ();--to pass in an argument as an array;2. Optional parameter: var a = a | | [];3. Variable-length arguments: A

Date 2015-11-28Move your previous reading notes before I lose them.Time past long, look back at the understanding are different. Here's a look at the differences with Java:JS is a kind of loose type language;JS does not distinguish between shaping numeric values and floating-point values, all numbers are represented by 64-bit floating-point type;No char;Special values: Infinity, NaN (not equal to yourself), Number.MAX_VALUE, Number.POSITIVE_INFINITY,Conversions and comparisons between various

Date: 2015-12-06 Event Propagation:1. Capture phase2. Operation Stage3. Foaming StageCookie and client persistence:;HTML5 introduced the Web application cache, Localstorage, sessionstorage;Using XMLHttpRequest:1. Create a XMLHttpRequest object;2. Specify an HTTP request and submit it to a server;3. Get the server's response synchronously or asynchronously;Processing XML, scripted client graphics, SVG, canvas, scripted applets, Flash intends to use to look again;The

Client memorySeveral forms of client storage:Web MemoryCookiesIE UserDataOffline applicationsWeb DatabaseFile System API20.1 Localstorage and Sessionstorage20.1.1 Storage expiration and scopeThe difference between Localstorage and Sessionstorage is that the storage has a different validity period and scope.The scope of the Localstorage is limited at the document source level.Document Source: protocol hostname port determines the same document sourceSource documents can share the same localstorag

One. Check whether it is a function.function Isfunction (x) {return Object.prototype.toString.call (x) = = = "[Object Function]";};function square (n) {return n*n;};Alert (isfunction (square)); trueI. Functional programming1. Working with arrays using functionsFor example:function fn () {//some code ...}; Elemnets.reduce (FN);2. Higher-order functions--functions of operation functionsFor example:Function not (f) {return function () {var result = f.apply (this,arguments);Return!result}};var even

1. function as a namespace. form: var Somefn = (function () {var a = 0;return function f () {//...};} ());2. closures. Parameters of an external function cannot be accessed directly within a closure unless the external argument is stored as a variable. For example: var outerarguments = arguments;3. Properties, methods, constructors of functionsA.Arguments.length; (expected number of arguments passed in)Arguments.callee.lenth; (number of actual arguments passed in)B. Prototype propertiesConstruct

object, wrapping the object to inherit all the methods of the string, and passing this wrapper object to. Length () to get the length, and return to the variable B, At the end of the process, B is assigned, the wrapper object is destroyed, and a does not change.The wrapper object is similar to the boxed Intiger object in Java for Int.In addition to strings string (), numbers and Booleans also have their own number () and Boolean () constructor methods to invoke. Of course, JS in addition to the

1./* ********************************** We can usually add methods to the prototype of a class, in this case: * To achieve the purpose of the extension, now to prohibit this extension. Only * required object.preventextentions (); ***********************************/function () { //to do// Invalid2.Object.seal (); // property cannot be deleted, but can be written and modified Object.seal (Object.prototype); Object.seal (Object.freeze);3. Set the properties of the object to read-only:

Real life of the real object did not find, in JavaScript left an object to another object, and I was dizzy to the unintelligible. Personnel are complex and people are difficult to understand. Although I am a liberal arts student, but also not good at Blarney. Or in the JS inside look for the object. So we start with the JS object today. Yesterday, we talked about the data types in JS are divided into two kinds, primitive type, object type. The c

9 1996" can also be accepted and parsed. However, the result Date object includes "Friday November 9 1996". JScript handles all of the standard time zones, as well as global standard times (UTC) and Greenwich Mean Time (GMT). Hours, minutes, and seconds are separated by colons. Although not all of these three items need to be specified. "10:", "10:11", and "10:11:12" are valid. Assuming a 24-hour clock is used, it is wrong to specify "PM" for the time after 12 o'clock noon.For example, "2

Classes and constructorsCalling the constructor with new creates a new object, and the prototype property of the constructor is used as a prototype for the new object.//constructor to initialize the newly created scope objectNo object was created and returnedfunctionRange (from, to) { This. from =From ; This. to =to ;} Range.prototype={includes:function(x) {return This. from This. To;}, foreach:function(f) { for(varx = Math.ceil ( This. from); X This. to; X + +) f (x); }, ToString:function()

do some more type checking if(t!== "Object" t!== "function")ThrowTypeError (); functionF () {};//Define a dummy constructor function.F.prototype = p;//Set its prototype property to P. return Newf ();//Use f () to create an "heir" of P.} 3. Query and settings for attributes1. Object as an associative arrayJavaScript objects are associative arrays, the difference between point access and parenthesis access2. Inheritance3. Property Access Errorvar len = Book book.subtitle book.subti

action to create an object instanceGood wording.function MyObject () {Code}Bad syntax: Start with a lowercase letterfunction MyObject () {Code}Bad wording: using underscoresfunction My_object () {Code}Bad writing: start with a verbfunction Getmyobject () {Code}Constants (variables that do not change values) should be named for all uppercase letters, separated by a single slide between different wordsGood wording.var total_count = 10;An object's properties are the same as a variable's naming con

access array elements is like accessing an object's properties in square brackets-that is, JavaScript converts the numeric index of an array into a string: that is, the index value 0 becomes "0", the index value 1 becomes "1", and then it is used as the property name. This can also be done for regular objects:var o={}; // create a Common object o[1]= "one"; Although described above, the special thing about arrays is that you can automatically main