dollar-sign

jQuery dollar sign ($) as function argument?

由 青春壹個敷衍的年華 提交于 2019-11-26 12:16:56
问题 I understand JavaScript closures, and I\'ve seen this done in native JS: (function () { // all JS code here })(); But, what does adding the jQuery spice do? (function ($) { // all JS code here })(jQuery); 回答1: Its a way of mapping jQuery to the $ in a way so that not all code in a page will see it. Maybe you have an existing script that uses jQuery that you like to reuse but you also use prototype that also uses $ in the same page. By wrapping any jQuery using code in that construct you

When/why to prefix variables with “$” when using jQuery? [duplicate]

由 天涯浪子 提交于 2019-11-26 09:26:41
问题 Possible Duplicate: Why would a javascript variable start with a dollar sign? I see people using the dollar sign in front of variables when using jQuery. Is there any reason behind this? I\'m I missing something basic or is it just a common practice? 回答1: It's a common reference to a jQuery wrapped object. It makes reading the code easier to know which variables are jQuery wrapped. //Item has been "cached" for later use in the script as a jQuery object. var $item = $(this); 回答2: For me a

What does $ mean/do in Haskell?

由 不羁岁月 提交于 2019-11-26 08:15:31
问题 When you are writing slightly more complex functions I notice that $ is used a lot but I don\'t have a clue what it does? 回答1: $ is infix "application". It's defined as ($) :: (a -> b) -> (a -> b) f $ x = f x -- or ($) f x = f x -- or ($) = id It's useful for avoiding extra parentheses: f (g x) == f $ g x . A particularly useful location for it is for a "trailing lambda body" like forM_ [1..10] $ \i -> do l <- readLine replicateM_ i $ print l compared to forM_ [1..10] (\i -> do l <- readLine

$ Variable in Chrome?

由 旧街凉风 提交于 2019-11-26 03:24:18
问题 I was working with the developer tools of google chrome on a page without jQuery (or any other library that uses the $ sign as a shortcut). When I inspected $ by the console (by just typing it in and hitting enter), i got this: $ function () { [native code] } So, chrome has some native function that can be referenced by $ . Only chrome seems to have this one and i cannot access it via window[\'$\'] nor via document[\'$\'] or this[\'$\'] . I was not able to find out what this function is. Do

What are &#39;$$&#39; used for in PL/pgSQL

由 守給你的承諾、 提交于 2019-11-26 00:33:45
问题 Being completely new to PL/pgSQL , what is the meaning of double dollar signs in this function: CREATE OR REPLACE FUNCTION check_phone_number(text) RETURNS boolean AS $$ BEGIN IF NOT $1 ~ e\'^\\\\+\\\\d{3}\\\\ \\\\d{3} \\\\d{3} \\\\d{3}$\' THEN RAISE EXCEPTION \'Wrong formated string \"%\". Expected format is +999 999\'; END IF; RETURN true; END; $$ LANGUAGE plpgsql STRICT IMMUTABLE; I\'m guessing that, in RETURNS boolean AS $$ , $$ is a placeholder. The last line is a bit of a mystery: $$

$ Variable in Chrome?

由 半世苍凉 提交于 2019-11-25 22:30:05
I was working with the developer tools of google chrome on a page without jQuery (or any other library that uses the $ sign as a shortcut). When I inspected $ by the console (by just typing it in and hitting enter), i got this: $ function () { [native code] } So, chrome has some native function that can be referenced by $ . Only chrome seems to have this one and i cannot access it via window['$'] nor via document['$'] or this['$'] . I was not able to find out what this function is. Do you know what it does and maybe have some background information on this? Thanks in advance! This has changed

What are the special dollar sign shell variables?

由 房东的猫 提交于 2019-11-25 22:00:20
问题 In Bash, there appear to be several variables which hold special, consistently-meaning values. For instance, ./myprogram &; echo $! will return the PID of the process which backgrounded myprogram . I know of others, such as $? which I think is the current TTY. Are there others? 回答1: $1 , $2 , $3 , ... are the positional parameters. "$@" is an array-like construct of all positional parameters, {$1, $2, $3 ...} . "$*" is the IFS expansion of all positional parameters, $1 $2 $3 ... . $# is the
订阅 dollar-sign