Basic knowledge of Java Script

Basic knowledge of Java Script
1. the basic data type JavaScript provides four basic data types for processing numbers and text numbers, String, Null, and Boolean 1 ). variable Syntax: var variable name = value; variable naming conventions: 1) variable names consist of letters, numbers, underscores, and $2) the first letter of the variable name must be a letter, $, or underline. 3) Reserved Words cannot be used in JavaScript. Note that the variable name is case sensitive. 2 ). type conversion parseInt (String) converts a String to an integer number parseFloat (String) and converts it to a float number 3 ). operator Arithmetic Operator +,-, *,/, %, ++, -- comparison operator = ,! =,>,> =, <, <= Logical operators &, | ,! 4 ). there are two types of single-line comment Syntax: // multi-line comment Syntax:/* Comment content */5 ). flow Control statement Syntax: if Condition Statement switch multi-branch statement for, while, do... The while LOOP statement break and the continue statement break interrupt the running of a loop. The continue statement is used to skip the remaining code blocks and directly go to the next loop for further execution. 6 ). function Definition and call. function declaration Syntax: function name (parameter list) {B. function code block; return expression;} c. function call Syntax: function name (real parameter 1, real parameter 2 ...); Var variable name = function name (real parameter 1, real parameter 2 ...); 7 ). variable scope based on the scope of the variable, variables in JavaScript can be divided into global variables and local variables 8 ). event Processing browser event onload, unonload, onsubmit mouse event onMouseMove, onMouseOver, onMouseOut, onMouseDown, onMouseUp text box event onchange, onselect, onfocus, onblur, 9 ). other onclick 2. browser Object Model Browser object model is a model used to describe the hierarchical relationship between objects. This object model provides an object structure that is independent of content and can interact with browser windows. 1 ). hierarchical Structure of browser objects common methods of window properties and method examples var money = prompt ("Enter withdrawal amount", 100 ); // receiving user input dialog box alert (money); // output 100 var state = conf REM ("your withdrawal amount is" + money); // The confirm and cancel button dialog box alert (state); // return true or false setTimeout ("called function ", "millisecond count") window. open ("adv.html", "", "related attributes"); height: window height; width: window width; top: The pixel value between the window and the top of the screen; left: the pixel value from the window to the left of the screen; toolbar: whether to display the toolbar; yes: display; menubar, scrollbars indicates the menu bar and scroll bar. Resizable: whether to change the window size. yes or 1 indicates whether to allow location: whether to display the address bar; yes indicates whether to allow status: whether to display information in the status bar; yes or 1 indicates yes; the role of the history object: The history object is used to manage the recently accessed URLs in the current window. Common Methods: Note: history. go (-1) is equivalent to history. back () history. go (1) is equivalent to history. forward () Example: <a href = "javascript: history. back () "> back </a> is equivalent to <a href =" javascript: history. go (-1) "> back </a> <a href =" javascript: history. forward () "> forward </a> is equivalent to <a href =" javascript: history. go (1) "> backward </a> locati On Object Function: location object is used to manage the URL Information of the currently opened window. common attributes and Methods: Example: window. location. href = "http://www.baidu.com"; 3. DOM overview DOM-Document Object Model is a set of Web standard DOM of W3C international organization. It is an interface document Object that has nothing to do with browsers, platforms, and languages: the document object represents the common attributes of the entire HTML document loaded in the browser window. Common Methods: document objects can access page elements in four ways. 1) document. all. page element name; 2) document. form name. element name; 3) document. getElementById ("ID name"); 4) document. getElementsByName ("element name ");-------------------------------- -------------------------------------------------------- 1. property example: Turn on the light and turn off the light <script type = "text/javascript"> function setColor _ () {var type = document. getElementById ("setColor "). value; if (type = "turn off the light") {document. getElementById ("setColor "). value = "turn on"; document. bgColor = "black";} else {document. getElementById ("setColor "). value = "turn off the light"; document. bgColor = "white" ;}}</script> 2. <input type = "button" value = "turn off the light" Id = "setColor" onclick = "setColor _ ()" name = "setColor"/> attribute example: the Core code of image advertisement scrolling with the scroll bar is as follows: 1. <script type = "text/javascript"> function move () {document. getElementById ("adv" ).style.top%400%document.doc umentElement. scrollTop + "px";} window. onscroll = move; </script> 2. <div id = "adv" style = "position: absolute; top: 400px; left: 10px; "> </div> example: select all the core code: 1. <scrip T type = "text/javascript"> function isChecked (state) {var v = document. getElementsByName ("lover"); for (var I = 0; I <v. length; I ++) {if (v [I]. type = "checkbox") {v [I]. checked = state ;}}</script> 2. <input type = "radio" name = "ischeck" onclick = "isChecked (true) "/> select <input type =" radio "name =" ischeck "onclick =" isChecked (false) "/> all <br/> <a href =" javascript: isChecked (true) "> select all </a> <a href =" javascript: isChe Cked (false) "> NO </a>