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- javascript - When should I use ?? (nullish coalescing) vs || (logical . . .
) in JavaScript only considers null or undefined as "nullish" values If the left-hand side is any other value, even falsy values like "" (empty string), 0 , or false , it will not use the right-hand side:
- Which equals operator (== vs ===) should be used in JavaScript . . .
JavaScript has two sets of equality operators: === and !==, and their evil twins == and != The good ones work the way you would expect The good ones work the way you would expect If the two operands are of the same type and have the same value, then === produces true and !== produces false
- How do you use the ? : (conditional) operator in JavaScript?
It's a little hard to google when all you have are symbols ;) The terms to use are "JavaScript conditional operator" If you see any more funny symbols in JavaScript, you should try looking up JavaScript's operators first: Mozilla Developer Center's list of operators The one exception you're likely to encounter is the $ symbol
- What does the !! (double exclamation mark) operator do in JavaScript . . .
A third use is to produce logical XOR and logical XNOR In both C and JavaScript, a b performs a logical AND (true if both sides are true), and a b performs a bitwise AND a || b performs a logical OR (true if at least one are true), and a | b performs a bitwise OR
- How does the double exclamation (!!) work in JavaScript?
In JavaScript, the values false, null, undefined, 0, -0, NaN, and '' (empty string) are "falsy" values All other values are "truthy " All other values are "truthy " (1):7 1 2 Here's a truth table of ! and !! applied to various values:
- What does ${} (dollar sign and curly braces) mean in a string in . . .
I haven't seen anything here or on MDN I'm sure I'm just missing something There's got to be some documentation on this somewhere
- Whats the difference between and in JavaScript?
This operator is almost never used in JavaScript Other programming languages (like C and Java) use it for performance reasons or to work with binary data In JavaScript, it has questionable performance, and we rarely work with binary data This operator expects two numbers and returns a number In case they are not numbers, they are cast to
- JavaScript OR (||) variable assignment explanation - Stack Overflow
That is, JavaScript "short-circuits" the evaluation of Boolean operators and will return the value associated with either the first non-false variable value or whatever the last variable contains See Anurag's explanation of those values that will evaluate to false
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