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Why is string concatenation faster than array join?

...ring concatenation. Beginning with version 1.0, the array technique is actually slower than using the plus operator in all cases. Other browsers have also optimized string concatenation, so Safari, Opera, Chrome, and Internet Explorer 8 also show better performance using the plus operator. Internet ...
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What is the 'new' keyword in JavaScript?

...n's external, accessible, prototype object (every function object automatically has a prototype property). It makes the this variable point to the newly created object. It executes the constructor function, using the newly created object whenever this is mentioned. It returns the newly created objec...
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Can you change what a symlink points to after it is created?

Does any operating system provide a mechanism (system call — not command line program) to change the pathname referenced by a symbolic link (symlink) — other than by unlinking the old one and creating a new one? ...
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Compare two DataFrames and output their differences side-by-side

...original question The first step is to concatenate the DataFrames horizontally with the concat function and distinguish each frame with the keys parameter: df_all = pd.concat([df.set_index('id'), df2.set_index('id')], axis='columns', keys=['First', 'Second']) df_all It's pr...
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Call static method with reflection

... I prefer simplicity... private void _InvokeNamespaceClassesStaticMethod(string namespaceName, string methodName, params object[] parameters) { foreach(var _a in AppDomain.CurrentDomain.GetAssemblies()) { foreach(var _t in _a.GetTypes()) { ...
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How can I set the Secure flag on an ASP.NET Session Cookie?

... There are two ways, one httpCookies element in web.config allows you to turn on requireSSL which only transmit all cookies including session in SSL only and also inside forms authentication, but if you turn on SSL on httpcookies you must also turn it on inside forms configuration to...
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What do the different readystates in XMLHttpRequest mean, and how can I use them?

...em except for 4. Some XMLHttpRequest implementations may let you see partially received responses in responseText when readyState==3, but this isn't universally supported and shouldn't be relied upon. share | ...
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html5 - canvas element - Multiple layers

...er, for zero lengths the unit identifier is optional (i.e. can be syntactically represented as the <number> 0)." w3.org/TR/css3-values/#lengths – xehpuk Feb 18 '16 at 23:00 ...
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How do I output coloured text to a Linux terminal?

... You need to output ANSI colour codes. Note that not all terminals support this; if colour sequences are not supported, garbage will show up. Example: cout << "\033[1;31mbold red text\033[0m\n"; Here, \033 is the ESC character, ASCII 27. It is followed by [, then zero o...
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Can dplyr package be used for conditional mutating?

...and the conditions (except for the default value of NA at the end) are mutually exclusive, as is the case in the question, then we can use an arithmetic expression such that each term is multiplied by the desired result using na_if at the end to replace 0 with NA. df %>% mutate(g = 2 * (a == 2 ...