Functions - Reading Assignment

Javascript Programming
#849

  1. How can you create a function in Javascript?
    Set the keyword “function” before and expression.

  2. What is the difference between var and let in regards to scope?
    Scope is the parameter in which data is defined by a binding. Var binding is applied throughout an entire script (global scope), while let or const bindings are defined to only a block of code.

  3. What is a pure function?
    A pure function is function which returns a value only based on it’s direct input with no regard to side effect’s of other code.

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#850
  1. A function is created with an expression that starts with the keyword function.
  2. Bindings declared with letare local to the block they are declared in. Bindings created with keyword var are visible throughout the whole function.
  3. A pure function is a function without side effects and that doesn’t rely on side effects from other code.
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#851

Functions Reading Assignment

  1. A function is created by an expression 'function funName(paramter1,parameter2...) {code to run}. Also uses 'let' or 'const' within local scopes, and 'var' in global snd within local functions as well. Pre 2015 var was used to create new scopes.
  2. var is used for global functions or local scopes, while let and const are used within local scope.
  3. A pure function gives a value with no side effects or changes in state, nor does it rely on outside information. A pure function will perform in the same way when given values.
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#852

Hi

I have the following question:

The snippet of code below is in the book (page 49); it is not clear to me how the binding “number” is defined.
Is “number” a arrow nested function inside of the “multiplier” function?
Where does “number” gets its value?
Perhaps the concept of Closure is not clear to me.
Please advise,

function multiplier(factor) {
return number => number * factor;
}
let twice = multiplier(2);
console.log(twice(5));

The output of this code is console prints // 10
Thanks!

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#853

1.- You can create a function in JavaScript in three forms:

  • Create a value to be function: let Myfunc = function (a) { return a+1;}
  • Declare a function: function Myfunc(a) { return a+1;}
  • Make a arrow function: let myFunc = a => a+1;

2.- The difference between "var’ and “let” is that “var” declares a global scope binding, and “let” is only within the scope of the block.

3.- A pure function is that which returns a value, vs the functions that do side effects.

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#854

  1. Start with the keyword function followed by parenthesis to contain parameters followed by an open curly bracket and a body, which contains the statements that are to be executed when the function is called. Finally a closing curly bracket.

  2. var acts like a global variable whose value re-declared and updated. let is limited to the containing block of code{} and it can be updated but not re-declared. const cannot be updated or re-declared.

  3. A pure function has the property that, when called with the same arguments, it always produces the same value (and doesn’t do anything else).

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#855
  1. A function is created (in its basic form) by using the function statement followed by the desired binding name for the function and then its parameters (comma separated and contained within round brackets). Following this an curly opening bracket defines the beginning of the block where the function code will be contained. Finally the block is closed by a curly closing bracket. eg

function name (para1, para1) {
code line 1
code line 2
}

  1. Variables defined with var are global (when outside of function). Variables defined with let only exist in the with the block of code in which they are defined.

3/ A pure function is one that has no dependencies outside of the function and the values passed to it. It will always return the same value for given inputs and can be substituted by the values the function would return without any effect on the operation of the whole program.

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#856
  1. You create a function by using
const functionName = function() {
// what code shall be executed
}
  1. var can be used globally, meaning that if var is defined inside of a function, if-statement etc. it is also defined when logging it to the console outside of that function. let can only be seen inside of functions; if you would define a let variable inside of a function and try to log it to the console, it would return an error.
  2. A pure function has no side effects and is not being altered by any surroundings, so it can be called in any environment and will always produce the same value (when given the same arguments).
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#857
  1. By starting the expression with the keyword “function” then the name of the function followed by the parameters assigned to that function. The function may or may not have parameters assigned.
  2. Var in regards to scope defines the variable globally in the program whereas let references the function for just the block it is in.
  3. A pure function is a function that when called with the same arguments will always produce the same output without any side effects.
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#858
  1. How can you create a function in Javascript?
    A: function displayName( parameters ) { code to execute }
  2. What is the difference between var and let in regards to scope?
    A: var-- binding is visible throughout the whole function; let-- binding is only local to the block it is declared in.
  3. What is a pure function?
    A: one that does not create any side effects
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#859

  1. How can you create a function in Javascript?
    A function os created by an expression that starts with the keyword function. Functions have set parameters, a body which contains statements that are to be executed when the function is called.

  2. What is the difference between var and let in regards to scope?
    Let- like const is only visible within the block it was created in. l
    Var- is visible outside the block it was declared in.

  3. What is a pure function?
    A pure function is a function where the return value is only determined by its input values, without observable side effects.

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#860

1. How can you create a function in Javascript?

You could do value:
*const testFunc = function() { *
//body of function
};

or declare a function:
function testFunc() {
//body
}

or arrow function:
let testFunc = (a,b) => a-b;

2. What is the difference between var and let in regards to scope?

var will be placed in the context of the nearest enclosing function while let will only exist in the scope of the nearest block that encloses it.
So a var defined in a for loop would exist outside the for loop as well while a let wouldn’t.

3. What is a pure function?

A function that has no side effect and the result is predictable and repeatable is pure function.

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#861
  1. you create a function essentially by defining a binding as a piece of code(function) that executes based on the parameters given.
  2. when you create a “let” binding inside a function the global program cannot see that binding. if you attempt to use that let binding that was defined inside a function outside of that function you will receive an error code. “var” bindings are global and can be used anywhere in the program. this is useful to isolate certain bindings and allow functions to operate in their local environment.
  3. a pure function produces no side effects. it only produces a value. a pure function can be called at any time and as long as the arguments given are the same it will always produce the same results.
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#862

  1. Using the word function and then giving it an expression.

  2. let is a variable limited to the scope of that section of code. var is used to define a global variable that can be call any time within the environment.

  3. A pure function is self contained. It will run inside itself with no side effects. It’s also disregards side effects from other code.

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#863

1 first name it as function then define what the function is then explain the possible var if any then explain the instructions
2let v.s. var
let is a local binding but var is global if written outside the parenthesis
3pure function = no side effects

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#864

*** How can you create a function in Javascript?**
The best way to create a function is by typing out function then (add parameters/agruments){enter function you want to be run} example function greet(name){console.log("Hey, "+name)}. The previous sentence defines the function. You must call the function for something to happen. Example greet(Dean)
*** What is the difference between var and let in regards to scope?**
let only works in the local scope it is being creating in, while var will work globally or at a bigger scope.
*** What is a pure function?**
A pure function is a function that always produces the same output per input and has no side effects. It is not effected by timing/order

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#865

  1. How can you create a function in Javascript?
    Ans: A function is created with an expression that starts with the keyword “function”

  2. What is the difference between var and let in regards to scope?
    Ans: Bindings declared with let are in fact local to the block that they
    are declared in, so if you create one of those inside of a loop, the code before and
    after the loop cannot “see” it. In pre-2015 JavaScript, only functions created
    new scopes, so old-style bindings, created with the var keyword, are visible
    throughout the whole function that they appear in—or throughout the global
    scope, if they are not in a function.

  3. What is a pure function?
    Ans: A pure function is a specific kind of value-producing function that not only
    has no side effects but also doesn’t rely on side effects from other code—for
    example, it doesn’t read global bindings whose value might change. A pure
    function has the pleasant property that, when called with the same arguments,
    it always produces the same value (and doesn’t do anything else).

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#866
  1. We create a function in Javascript with an expression that starts with the keyword function.
  2. The difference between var and let in regards to scope is that let is declared locally to the block it is declared within whereas var appears throughout the global scope so long as it is not within a function.
  3. A pure function is where regardless of the input, it is always going to give the same output.
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#867

How can you create a function in Javascript?

A function is created by assigning the keyword function to a variable that we declared, and then assigning the parameters to the function.

What is the difference between var and let in regards to scope?

The difference between var and let is that functions created with var are visible throughout the entire program, or function, if they are in a function, whilst let is only visible locally, so for example if you create a function with let inside of a loop that function will only be visible inside that loop.

What is a pure function?

A pure function is a function that always returns a value, and it doesnt matter when or where you call it i will always give you the right value, if asked correctly.

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#868

  1. How can you create a function in Javascript?
    function name(parameters) {code}

  2. What is the difference between var and let in regards to scope?
    Let is scoped for the current block
    var is scoped for the program.

  3. What is a pure function?
    a pure function is specific type of value producing function with no side effects and it doesn’t rely on other side effects.

1 Like