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How do I check if an array includes a value in JavaScript?

Modern browsers have Array#includes, which does exactly that and is widely supported by everyone except IE: Run code snippet You can also use Array#indexOf, which is less direct, but doesn’t require polyfills for outdated browsers. Run code snippet Many frameworks also offer similar methods: jQuery: $.inArray(value, array, [fromIndex]) Underscore.js: _.contains(array, value) (also aliased as _.include and _.includes) Dojo Toolkit: dojo.indexOf(array, value, [fromIndex, findLast]) Prototype: array.indexOf(value) MooTools: array.indexOf(value) MochiKit: findValue(array, value) MS … Read more

javac is not recognized as an internal or external command, operable program or batch file [closed]

I am experiencing an error while trying to compile Java programs. I am on Windows (this is a Windows-specific problem) and I have the latest JDK installed. I have attempted a solution involving the PATH variable, but the error persists. Console output:

What is tail recursion?

Consider a simple function that adds the first N natural numbers. (e.g. sum(5) = 0 + 1 + 2 + 3 + 4 + 5 = 15). Here is a simple JavaScript implementation that uses recursion: If you called recsum(5), this is what the JavaScript interpreter would evaluate: Note how every recursive call has to complete before … Read more

How to re-enable right click so that I can inspect HTML elements in Chrome?

If they have just changed the oncontextmenu handler (which is the most straightforward way to do it), then you can remove their override thus: Otherwise, if it is attached to individual elements, you can get all the page’s elements, and then remove the handler on each one: Or, it seems you can turn off such scripts; via an … Read more

What is the difference between “INNER JOIN” and “OUTER JOIN”?

Assuming you’re joining on columns with no duplicates, which is a very common case: An inner join of A and B gives the result of A intersect B, i.e. the inner part of a Venn diagram intersection. An outer join of A and B gives the results of A union B, i.e. the outer parts of a … Read more

Replacing instances of a character in a string

Strings in python are immutable, so you cannot treat them as a list and assign to indices. Use .replace() instead: If you need to replace only certain semicolons, you’ll need to be more specific. You could use slicing to isolate the section of the string to replace in: That’ll replace all semi-colons in the first 10 characters of the … Read more

How am I supposed to use index.html?

Many web servers will have a ‘default document’ that is returned when you specify just a path and no file name. So browsing to http://example.com will return the default document from the document root directory of that domain. Quite often the default document can be named index.html, index.htm or -if PHP is installed- index.php, but … Read more

What is the := operator?

In all languages that support an operator := it means assignment. In languages that support an operator :=, the = operator usually means an equality comparison. In languages where = means assignment, == is typically used for equality comparison. does := mean =? I can’t recall any languages where := means the same as =. In MySQL := and = are both used for assignment, however they are not interchangeable and selecting the correct one … Read more

warning: implicit declaration of function

You are using a function for which the compiler has not seen a declaration (“prototype“) yet. For example: You need to declare your function before main, like this, either directly or in a header:

javac is not recognized as an internal or external command, operable program or batch file [closed]

Closed. This question is not reproducible or was caused by typos. It is not currently accepting answers. Want to improve this question? Update the question so it’s on-topic for Stack Overflow. Closed 7 years ago.Improve this question I am experiencing an error while trying to compile Java programs. I am on Windows (this is a Windows-specific problem) and I have the … Read more

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