What does require('module')(parameter); mean? [duplicate] - javascript

This question already has answers here:
What does double parentheses mean in a require
(3 answers)
Closed 7 years ago.
In Node.js what does what does var module = require('module')(parameter); mean?
Is it the same as:
var module = require('module');
mod = module(parameter);


This is the same as :
var mod = require('module'),
module = mod(parameter);
That's just mean that require('module') returns a function. require(...) can returns anything, it can be an object, a string, a function, anything.

Related

Extra parameters in a self executing function? [duplicate]

This question already has answers here:
What does the comma operator do in JavaScript?
(5 answers)
Closed 1 year ago.
I saw this piece of code in a webpack compiled file
(1,2, function(x) {
console.log(x);
return 4;
})(5);
This seems to execute correctly. I am aware the 5 is a parameter to function(x)
I don't understand what the 1,2 are? How is this valid?

Well, it's because the brackets only returns the function
(thing1,thing2,thing3,thing4....,thingN) would show the last thing on the list(in this case, thingN)
Example
var bracketTest1=(1,3,5,7,9,null)
console.log(bracketTest1) //null
var bracketTest2=(null,1,2,3,4)
console.log(bracketTest2) //4
var bracketTest3=(null,1,2,4,5,function(x){return x})
console.log(bracketTest3) //function(x)
console.log(bracketTest3(Object)) //function Object()
console.log((1,2,3,4,null,undefined)) //prints undefined

How is this string as a function argument working (no parentheses?!)? [duplicate]

This question already has answers here:
Backticks (`…`) calling a function in JavaScript
(3 answers)
Closed 1 year ago.
Is this a new way to call a function? Whats this even called? Why do this?
const foo = a => console.log(a)
const k = foo`stuff here?` //whaaaaaaa
//output is ["stuff here?"]

they are called tagged template functions. You can read more on how they work and what they do here: MDN

Why does. this arrow function not return an error? [duplicate]

This question already has answers here:
Value returned by the assignment
(5 answers)
Declaring variables without var keyword
(8 answers)
Closed 2 years ago.
In this function the cm variable has no data type eg var const or let. How does it still work without giving me an error?
const inchToCm = inch => cm = inch * 2.54;
Is it because it used an implicit return?

Is it possible to create a ES6 Javascript expression whose value is an object with a dynamic property name? [duplicate]

This question already has answers here:
How to use a variable for a key in a JavaScript object literal?
(16 answers)
Closed 4 years ago.
I currently do:
function outer(prop_name) {
const tmp = {};
tmp[prop_name] = 'hello world';
foo(tmp);
}
Is there a way of rewriting this as:
foo(<expression>)
using an expression involving prop_name?

You can write it as
foo({ [prop_name] : 'hello_world'});

Calling javascript function using dot operator [duplicate]

This question already has answers here:
How to observe value changes in JS variables
(3 answers)
Closed 5 years ago.
function getPercCalculated(x){
return (x*9.3)/100;
}
var x = 10;
var perx = getPercCalculated(x);
Instead of this I would like to call the getPercCalculated using dot operator like
var perx = x.getPercCalculated()
Can someone help me..!!

Number.prototype.getPercCalculated= function(){
return (this*9.3)/100;
};
This will attach the getPercCalculated to every number in your code tough

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