javascript web scraping example

. Htmlconnection Object Solution Copy Code code as follows: var items = document.getelementsbytagname ("div"); var len = items.length for (var i = 0; i .......................................... . } In this way, the efficiency is basically the same as the normal array. Create a script label dynamically It takes a while to load and execute a JavaScript script, and in our program, some

to useYou can use comparison operators to compare values in a conditional statement and then take action based on the result:if (ageYou'll learn more about conditional statements in the next section of this tutorial.logical operatorsLogical operators are used to determine the logic between variables or values.Given X=6 and y=3, the following table explains the logical operators: Operator Describe Example

the interval is $action_time, we assume that it is executed once per hour. That is $action_time=3600 (the exact value is obtained from your initialization table). can also be obtained according to the city level or the user level. Anyway, whatever you want to set it. ） At this point, there is a basic time. There is a basic capital production. There's a time interval. Let it loop and execute it. As mentioned above, the server uses the C language timer. The client uses

PuppeteerThe Google Chrome team's puppeteer is an automated test library that relies on nodejs and chromium, and its biggest advantage is that it can handle dynamic content in Web pages, such as JavaScript, to better impersonate users.Some web site anti-crawler means to hide some of the content in some Javascript/ajax

traversal, the parent node of the construction tree and the child node for (i = 0; i The complete code for spanning the tree with JavaScript is as followsRegional data var = [{"Code": 420000, "name": "Hubei Province", "Parentcode": 0},{"code": 420100, "name": "Wuhan", "Parentcode": 420000}, {"Code": 420101, "name": "District", "Parentcode": 420100},{"code": 420102, "name": "Jiang ' an", "Parentcode": 420100},{"code": 4201 "Name": "Jianghan District",

Example: using JavaScript to operate strings (some string functions) to operate string values is common for developers. There are many methods to operate on a string, such as extracting part of the content from a string or determining whether a string contains a specific character. The following JavaScript Functions provide developers with all the functions they

This article mainly introduces Node. examples of simple web page capturing functions implemented by js. This article uses libraries such as PhantomJS and node-phantomjs to implement these functions. For more information, see the following: web page capturing is a well-known technology, however, there are still a lot of complexities. Simple Web crawlers are still

This article illustrates the concept and usage of JavaScript function throttling. Share to everyone for your reference, specific as follows: Recently in the Web page when there is a need, is the browser window changes need to change some of the page element size, it is natural to think of the window resize events, so I wrote the The function is implemented, but I drag the way to change the si

final 1, within which the page can still respond to mouse keyboard events. Click the Stopworker button, the Web worker will be terminated directly, the page change display will stop directly.Embedded web WorkerThere is no official way to embed worker code in a Web page like a script tag. However, if a SCRIPT element is not specified src属性，并且它的 type as a mime-typ

JavaScript, the world's most popular programming language, has been labeled as a nightmare for Web development designers, and while the real nightmare is the DOM API, the scripting language that has been exploited by a large number of developers and designers to augment their Web front end is now gaining weight, though, JavaS