It’s a time zone change on December 31st in Shanghai. See this page for details of 1927 in Shanghai. Basically at midnight at the end of 1927, the clocks went back 5 minutes and 52 seconds. So “1927-12-31 23:54:08” actually happened twice, and it looks like Java is parsing it as the later possible instant … Read more
Preliminaries JavaScript has only one data type which can contain multiple values: Object. An Array is a special form of object. (Plain) Objects have the form {key: value, key: value, …} Arrays have the form [value, value, …] Both arrays and objects expose a key -> value structure. Keys in an array must be numeric, … Read more
ECMAScript 6 introduced String.prototype.includes: const string = “foo”; const substring = “oo”; console.log(string.includes(substring)); // true includes doesn’t have Internet Explorer support, though. In ECMAScript 5 or older environments, use String.prototype.indexOf, which returns -1 when a substring cannot be found: var string = “foo”; var substring = “oo”; console.log(string.indexOf(substring) !== -1); // true 6 solved How to check whether … Read more
The element you were trying to find wasn’t in the DOM when your script ran. The position of your DOM-reliant script can have a profound effect on its behavior. Browsers parse HTML documents from top to bottom. Elements are added to the DOM and scripts are (generally) executed as they’re encountered. This means that order … Read more
Yes, it was added in version 2.5. The expression syntax is: a if condition else b First condition is evaluated, then exactly one of either a or b is evaluated and returned based on the Boolean value of condition. If condition evaluates to True, then a is evaluated and returned but b is ignored, or … Read more
Data Storage: Specify the utf8mb4 character set on all tables and text columns in your database. This makes MySQL physically store and retrieve values encoded natively in UTF-8. Note that MySQL will implicitly use utf8mb4 encoding if a utf8mb4_* collation is specified (without any explicit character set). In older versions of MySQL (< 5.5.3), you’ll … Read more
The difference is that functionOne is a function expression and so only defined when that line is reached, whereas functionTwo is a function declaration and is defined as soon as its surrounding function or script is executed (due to hoisting). For example, a function expression: // TypeError: functionOne is not a function functionOne(); var functionOne … Read more
No output before sending headers! Functions that send/modify HTTP headers must be invoked before any output is made. summary ⇊ Otherwise the call fails: Warning: Cannot modify header information – headers already sent (output started at script:line) Some functions modifying the HTTP header are: header / header_remove session_start / session_regenerate_id setcookie / setrawcookie Output can … Read more
Introduction Headers already sent error is a common issue encountered by PHP developers. This error occurs when the server sends the response to the browser before the header information is sent. This can be caused by a number of things, such as extra whitespace, incorrect line endings, or even a missing semicolon. Fortunately, this error … Read more
Is Java “pass-by-reference” or “pass-by-value”? solved Is Java “pass-by-reference” or “pass-by-value”?
Introduction Java is a popular programming language used by developers around the world. One of the most common questions asked about Java is whether it is a “pass-by-reference” or “pass-by-value” language. This article will explain the difference between the two and provide an answer to the question. It will also discuss the implications of the … Read more
PHP mail function doesn’t complete sending of e-mail solved PHP mail function doesn’t complete sending of e-mail
Introduction The PHP mail function is a powerful tool for sending emails from a web server. However, there are times when the mail function does not complete the sending of an email. This can be due to a variety of reasons, such as incorrect server settings, incorrect syntax, or a lack of resources. In this … Read more
This depends a lot on what you mean by “revert”. Temporarily switch to a different commit If you want to temporarily go back to it, fool around, then come back to where you are, all you have to do is check out the desired commit: # This will detach your HEAD, that is, leave you … Read more
Note: The ideas here are pretty generic for Stack Overflow, indeed questions. Disclaimer: Writing a good question is hard. The Good: do include small* example DataFrame, either as runnable code: In [1]: df = pd.DataFrame([[1, 2], [1, 3], [4, 6]], columns=[‘A’, ‘B’]) or make it “copy and pasteable” using pd.read_clipboard(sep=’\s\s+’), you can format the text … Read more