How do you use the ? : (conditional) operator in JavaScript?
2011年6月7日 · 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 …
Because JavaScript has what are called "truthy" and "falsy" values, there are expressions that when evaluated in other expressions will result in a true or false condition, even though the value or expression being examined is not actually true or false.
Which equals operator (== vs ===) should be used in JavaScript ...
2008年12月11日 · 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 .
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:
What is the purpose of the dollar sign in JavaScript?
Unlike many similar languages, identifiers (such as functional and variable names) in Javascript can contain not only letters, numbers and underscores, but can also contain dollar signs. They are even allowed to start with a dollar sign, or consist only of a dollar sign and nothing else. Thus, $ is a valid function or variable name in Javascript.
What does ${} (dollar sign and curly braces) mean in a string in ...
2016年3月7日 · 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.
What is the difference between != and !== operators in JavaScript?
2021年1月5日 · Also at In JavaScript, is '!=' the same as '!=='?. More answers, but this is the duplicate target. More answers, but this is the duplicate target. – Peter Mortensen
Difference between == and === in JavaScript - Stack Overflow
2009年2月7日 · JavaScript has both strict and type-converting equality comparison. For strict equality the objects being compared must have the same type and: Two strings are strictly equal when they have the same sequence of characters, same length, and same characters in corresponding positions.
String interpolation in JavaScript? - Stack Overflow
2014年7月20日 · Consider this code: var age = 3; console.log("I'm " + age + " years old!"); Are there any other ways to insert the value of a variable in to a string, apart from string concatenation?
javascript - What does [object Object] mean? - Stack Overflow
In JavaScript there are 7 primitive types: undefined, null, boolean, string, number, bigint and symbol. Everything else is an object. Everything else is an object. The primitive types boolean , string and number can be wrapped by their object counterparts.