javascript - What does the ! (exclamation mark) mean before selector in jQuery -

-

इस सवाल का पहले से ही एक उत्तर है: < / P>

  • 2 जवाब

मुझे पहले से ही पता है कि < कोड>! को सामान्यत: "code" नहीं , नहीं , और null में जावास्क्रिप्ट में अभिव्यक्त करने के लिए उपयोग किया जाता है।

लेकिन jQuery के चयनकर्ता से पहले उद्गार चिल्लाना क्या मतलब है? 

  यदि (! $ ('चयनकर्ता')। हैक्सेल ('कुछ')) {कुछ करो}  < 
 
 
 
 
 
 
 यह एक बूलीयन को अस्वीकार करता है। 
 
 अर्थ: 
 
 
 
 
 और 
 
 
 गलत हो जाता है 
 
 
 
 इस उदाहरण में इसका मतलब है: 
 <पूर्व>  यदि (! $ ('चयनकर्ता')। हैक्लास ('कोई चीज़    हैक्लासेल  फ़ंक्शन के परिणाम पर। ऐसा है जैसे आपने ब्रैकेट्स का उपयोग किया है (लेकिन आपको ब्रैकेट्स का उपयोग नहीं करना है, जावास्क्रिप्ट जानता है कि इसका मतलब है)। 
 
 ! ($ ('Selector')। हैक्लास ('कुछ' ) / * उदाहरण के लिए रिटर्न सही * /) / * अब यह झूठी है * /

Comments

Post a Comment

Popular posts from this blog

java - org.apache.http.ProtocolException: Target host is not specified -

-
I have written a simple httprequest / response code and I am getting this error below: I used to type in my classpath httpclient, httpcore, common -Codecs and general logging. I am very new to Java and I do not know what's going on here. Please help me. code: import org.apache.http.client.HttpClient; Import org.apache.http.client.methods.HttpGet; Import org.apache.http.HttpResponse; Import org.apache.http.impl.client.HttpClientBuilder; Import org.apache.http.Header; Import org.apache.http.HttpHeaders; Public class UnshorteningUrl {public static zero main (string [] args throws exception {HttpGet request = zero; HTTP Client Client = HTTP ClientBuilder.credit (). Build (); Try {Request = New HTTP Gate ("trib.me/1lBFzSi"); HttpResponse httpResponse = client.execute (request); Header [] header = httpResponse.getHeaders (HttpHeaders.LOCATION); // Preconditions.checkState (headers.length == 1); String new url = header [0] .getValue (); System.out.println ("new url...
Read more

How to access user directory in lazarus? -

-
After I am trying to open file changelog.txt and it does not matter if I open it Need to have the user open it though it is always located in the ~ / directory. Enter the file here. Here is my code: Process TForm1.FormCreate (From: TObject); Var myFile: textfile; Line: String; Start AssignFile (myFile, '~ / changelog.txt'); Reset (myFile); While EOF (MyFile) does not readLn (myFile, Line); Label3.Caption: = (Label3.Capttion + Line + # 13 # 10); End; CloseFile (myFile); End; This does not work, however, if I replace ~ with the actual user name, then it works, however, I use the username of each user Can not know which will run my program. Any idea how can I get the username that started the program? ! Thanks Edit1: I have tried this, but this also includes a new line: RunCommand ('/ bin / bash', ['- - C ',' Whoami '], users); This is normal. The concept of "~" is an shell level and thus requires a separate shell elev...
Read more

html - Trouble with image gallery on codepen -

-
I get my first project html & amp; CSS, but there is some problem. I am practicing using Codepean and my gallery was running well but I am trying to add the last line of images and it is all messing up and I do not know why For some reason, when I try to add that chess board it all gets worse. I am still very new so I hope to learn a lot. Thank you. [1]: http://codepen.io/zenturtle/pen/ezDGC Margins are causing issues when you use margins in the position of an element, then you push the elements around it too. Use a solution: Status: Relative and then use Positioning Properties: Above , Below , left , right example: #chess {status: relative; Left: 555px; } Another solution is to use status: absolute . Location Location: Relative on & lt; Div id = "perimeter" & gt; Status: Full on every Example: #chess {status: full; Bottom: 122px; Correct: 230px; } Similarly you are in the position of chess image...
Read more