Check if value exists in firebase database

Is there a way in firebase to check if a value exists in the database? Firebase has method .exists() but according to the documentation it only checks the key. I have the following structure: {"users":{"-KKUmYgLYREWCnWeHCvO":{"fName":"Peter","ID":&qu...

P粉354602955 2023-08-27 19:51:39 0  2  447

How to check if an array contains a value in JavaScript?

What is the cleanest and most efficient way to find out if a JavaScript array contains a value? This is the only way I know: functioncontains(a,obj){for(vari=0;i<a.length;i++){if(a[i]===obj){returntrue;}}returnfalse;} there Isn't there a better, cleaner way to achieve this? This is most simil...

P粉592085423 2023-08-23 11:09:10 0  2  452

How to determine whether nginx uses epoll

The nginx documentation says that it can automatically select the appropriate method: {code...} Use epoll is not specified in the configuration file. How to determine whether nginx uses epoll?

过去多啦不再A梦 2017-05-16 17:19:03 0  3  893

Check if record exists in any column

In my Laravel application I need to check if there is a specific record in 20 columns in a table. I have searched for this answer but only found a way to check if it exists in a specific column but I need to check all columns and I was wondering if there is a way to do this without a loop, For examp...

P粉917406009 2024-04-01 15:20:21 0  1  496

linux - How do I know if gcc g++ is installed in my centos?

I want to know how to know if gcc g++ is installed in my system

我想大声告诉你 2017-05-27 17:44:48 0  6  992

javascript - How to tell if the user has switched to the current tab?

I noticed that YouTube only starts playing videos when the user switches to the current tab. So when a user opens multiple tabs, how to determine whether the user has switched to the current tab?

三叔 2017-07-05 10:38:13 0  2  877

How to determine whether the database libraries and tables exist?

For example, how to determine whether the database libraries and tables exist?

正念的奇迹 2017-08-08 10:47:41 0  2  1249

How to check if a URL exists via PHP?

How to check if a URL exists (not 404) in PHP?

P粉288069045 2023-08-23 22:39:16 0  2  469

How to determine if composer is installed successfully?

How to determine if composer is installed successfully?

我爱Java 2018-02-19 13:32:39 0  3  1737

javascript - How to know if a string contains special characters?

For example: var regVal = '\w+'; How to know if it contains a backslash?

滿天的星座 2017-05-19 10:38:52 0  1  562

javascript - How to determine whether an app is installed on iOS on a mobile web page?

On the mobile web page, how to determine whether an app is installed on iOS?

学习ing 2017-07-01 09:12:24 0  1  1059

Hello, newbie, how do you check if this happens?

Hello, newbie, how to check if this happens?

风木 2019-05-23 16:27:02 0  2  1151

How to use mysqli to determine whether a MySQL database exists in PHP?

How to use the mysqli statement in PHP to accurately determine whether a MySQL database exists? In addition, how to determine whether a table in the database exists? In addition, what do the two styles provided in the official PHP documentation mean? Object-oriented style and process-oriented style....

淡淡烟草味 2017-06-14 10:49:52 0  1  1071

How can I know that the image path is written correctly?

How can I know that my path is written correctly? Why can’t I always want to know!!!!! How do I write the path correctly?

小小小布遛. 2020-08-30 15:52:28 0  3  3091

javascript - How to see what technical framework is used on the website?

How to check what technical framework is used on the website? Are there any other browser plug-ins besides wappalyzer?

为情所困 2017-06-26 10:56:15 0  3  1151

How to check time between two date variables in php?

I have 3 variables, which are 3 numbers (day, year, month). Together they become a date type variable. Additionally, I have a date variable that represents the current date. How can I check if the first date is 13 years or more before the current date? Here is my code: $usersday=(int)$_POST['day'];$...

P粉831310404 2023-08-16 13:21:21 0  1  595

How to check if coordinates are inside bounds object in PHP?

I have some coordinates and I want to check if these coordinates are exactly within the Google Maps bounds (Northeast and South West). Example: AvailableLat:40.712776AvailableLong:-74.005974 I want to know if the coordinates above are within the bounds below: >bounds_north_east[lat]28.63713261089...

P粉101708623 2024-04-05 00:25:54 0  1  1559

How to check whether the save is successful?

May I ask what the teacher uses to check whether the save is successful?

傻傻de。發呆 2018-07-24 13:22:41 0  0  1188

javascript - How to determine if the columns of bootstrap table mergecells have been loaded?

Use bootstrap table options to set up a table, and hope to use the mergeCells method to merge cells, but now I don’t know how to determine whether the columns have been loaded?

高洛峰 2017-05-19 10:15:21 0  1  984

Check if a PHP string consists only of integers

I'm writing PHP code to validate some data entered by the user, one of them is an integer and I'm using $_REQUEST["age"] to get it, when I use gettype($_REQUEST["age"])=="integer" and is_int($_REQUEST["age"]) to check if this value is an integer, both return f...

P粉788765679 2023-09-21 21:52:44 0  2  644