Functions - Reading Assignment

Javascript Programming
#628

  1. How can you create a function in Javascript?
    A Function is created with an expression that starts with the keyword function. Functions have a set of parameters and a body, which contains the statements that are to be executed when the function is called. The function body of a function created this way must always be wrapped in braces, even when it consists of only a single statement.

  2. What is the difference between var and let in regards to scope?
    Bindings declared with the var keyword are visible throughout the whole function that they appear in, bindings with the keyword let are only visible to that block they are created in.

  3. What is a pure function?
    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. 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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#629
  1. You can create a function in Javascript by writing an expression that starts with the keyword “function.” Then the function can have parameters and a body, which includes that statements that will be executed when the function is called.
  2. Bindings that are made with let are only recognized within the block that they’re written in, while var is visible throughout the whole scope. Let is local while var is global.
  3. A pure function is a kind of value-producing function that produces no side effects and also doesn’t rely on side effects from other code.
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#630

  1. A function starts with the keyword function followed by the name you want to give it and then , in round brackets, you may ( or not ) put the parameters.

  2. var bindings are function scoped so they can be seen throughout the whole function. When not in a function they are visible to the global scope.

    let functions are block scoped so they are local to the code block where they are created. Cannot be seen by blocks before or after.

  3. A pure function, given the same input always return the same output…no side effects involved.

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#631

  1. A function is created with an expression that starts with the keyword function, followed by a name, followed by parentheses. Function names can contain letters, digits, underscores, and dollar signs (same rules as variables). The parentheses may include parameter names separated by commas:
    ( parameter1, parameter2, … )
    The code to be executed, by the function, is placed inside curly brackets.

  2. let allows you to define a variable that is limited in scope to the block they are declared in. Whatever variable you define using var will be visible throughout the whole function that they appear in, or throughout the global scope, if they are not in a function.

  3. A pure function when called with the same arguments will always will always produce the same value. It wont try to change variables out of its scope and it doesnt produce any side effects.

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#632

  • How can you create a function in Javascript?
    A function is created with an expression that starts with the keyword…function

  • What is the difference between var and let in regards to scope?
    Bindings declared with let are local and to the block they are declared in, var keywords are visible throughout the whole function that they appear in or throughout the global scope if they are not in a function

  • What is a pure function?
    Given the same input it’s always going to return the same output without side effects

Does someone know a good clear example of recursion, i understand the concept, but …not completely getting it. Thanks!

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#633

1. A function is created with an expression that starts with the keyword function.Functions have parameters and some dont.

2. let allows you to declare variables that are limited in scope to the block, statement, or expression on which it is used. var keyword means a variable global, or local variable.

3. a pure function is a function which:

Given the same input, will always return the same output and Produces no side effects

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#634
  1. function fname(parameter1, parameter2) { code you want to execute }
  2. let is for a smaller scope, in one block. var is global
  3. A pure function is a function that doesn’t have any side-effects and doesn’t rely on side-effects from other code.
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#635
  1. How can you create a function in Javascript?
    A function is created with an expression
    that starts with the key word function . Functions have a set of parameters (in this case, only x) and a body, which contains the statements that are to be executed when the function is called. The function body of a function created this way must always be wrapped in braces, even when it consists of only a single statement.
  2. What is the difference between var and let in regards to scope?
    The main difference is the scope difference, while let can be only available inside the scope it’s declared, like in for loop, var can be accessed outside the loop.
  3. What is a pure function?
    A pure function is a function where the return value is only determined by its input values, without visible side effects.
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#636
  1. A function is composed of an expression the keyword function, which might have or not parameters, and a body whitch contains the statements that are to be executed when the function is called
const square = function(x) {
   return x * x;
};

  1. Let is limited to a block and can not be seen outside of it, while var defines a variable with a larger scope, local within a function or global.

  2. Pure functions has no side effect, it doesn’t read a global bindings whose value might change. When it called with the same argument it always produces the same value (and doesn’t do anything else).

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#637

1.to create a function in Javascript
function functionName(var1,var2,…){ code to be executed}

2.let are variables declared limited to a block scope whereas var can be both block scope or global (outside block scope).

  1. Pure function is a value producing function of same value and has no side effects or rely side effects.
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#638

  1. To create a function in JavaScript we use the keyword function followed by the name we are calling the function and then parenthesis.

  2. Var can be defined locally or globally depending on where you use it in the code. For let this is limited to the scope of the statement.

  3. A pure function is a function that will always return the same output as long as the same input is inserted and they do not produce side effects.

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#639

  1. A function is created with an expression that starts with the keyword function, then an optional set of parameters, and a body of statements to be executed when the function is called

  2. let and const are local to the block they are declared in, var can be local or global

  3. A pure function has no side effects, doesn’t rely on side effects from other code, and when called with the same arguments will always return the same value

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#640
  1. There are may ways, here it is an example of arrow deffinition:
    const isEven = (number) => {
    return (number % 2 === 0);
    }
    Use example:

isEven(1)
false
isEven(8)
true

  1. Let creates a new binding that is local in scope. Var designates a global existing binding, where the value can be accesed and modified from outside of the function.

  2. A pure function gives a result only dependent on the provided parameters. Everytime the the function is called with the same parameter it will return the same result.

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#641
  • How can you create a function in Javascript?
    There are three ways of creating functions
    // Define f to hold a function value
    const f = function(a) {
    console.log(a + 2);
    };

// Declare g to be a function
function g(a, b) {
return a * b * 3.5;
}

// A less verbose function value using arrows
let h = a => a % 3;

  • What is the difference between var and let in regards to scope?
    LET allows the function to be seen within the current scope and not visible to the global or outside scopes.
    VAR ends up in the nearest function scope or the global scope

  • What is a pure function?
    A PURE function is a specific kind of value-producing function that not only has no side effects but also does not rely on the side effects from other codes, so for instance it doesn’t read global bindings which might have changed

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#642

Excellent answer @Dragutin ! :slight_smile:
There’s a small discrepancy in the answer and thought would be great if I clear it out for you.

In the above statement, you mentioned that var can be accessed from outside the function. This is not entirely true. If var is defined in an enclosing function, the scope is restricted to that function itself. It is only when var is defined outside all functions that it becomes a global variable.

Hope this clears it out.

Happy Learning! :smiley:

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#643
  1. By making a set of parameters and pairing it with a body that contains the statements to be executed.
    function x(a,b) {c,d,e}
  2. let can only be seen in the local block or loop inside the scope while var is seen throughout the whole function and appears on the global scope.
  3. A pure function gives the same result if it has the same parameters and doesn’t change the variables outside of it’s scope.
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#644

  1. You can create a function with an expression that starts with the keyword, function.

  2. The difference between the two are that the bindings declared with let are 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. While bindings declared with var behave differently, with them usually ending up in the nearest function scope or the global scope, no matter what block the function is.

  3. It is a specific kind of value-producing function that doesn’t have and rely on side effects from other code, it produces the same value and doesn’t read global bindings whose value might change.

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#645
  1. How can you create a function in Javascript?

We can create a function with an expression that start with the word function and contains:

  • a set of parameters
  • Body that contain statements to be executed when the function is called.
  1. What is the difference between var and let in regards to scope?

Bindings created with “let” are considered local to the block, mean that are not visible outside the designed block. , while with var is visible throughout the global scoop.

  1. What is a pure function?

Is a specific kind of value-producing function that doesn t that has no side effect and doesn t rely to any from other code. It is always producing the same value when is called with the same agruments.

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#646
  1. How can you create a function in Javascript?
    Functions have a set of parameters and a body, which
    contains the 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 is local and refers to the block. But when used outside the function they refer to the whole programme.
  3. What is a pure function?
    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.
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#647

  1. To create a function in Javascript, (1) start with the keyword function. This will allow either Atom or the console in your Web browser to open a function. (2) Include a set of parameters (i.e. base and exponent to find a power). (3) Include a body that will contain the statements that you want to execute when you call the function.

  2. In regards to scope, let is local only to the block in which it is declared; the code before and after the loop cannot “see” it. On the other hand, var is visible throughout the entire function you are creating.

  3. A pure function is a specific kind of value-producing function that neither has side effects nor relies on side effects from another code. For example, it does not read global bindings whose value could change. Instead, it always gives the same value when it is called with the same arguments.

After I read the chapter but before I posted these answers, I tried playing around with two of the functions that were demonstrated in the book, the one for finding the square of a number and the one for finding the power of a number. (A square is really a power, as in 2 squared, in which 2 * 2 = 4. But a power can also be a higher number, such as 3, 4, 5, etc.) I don’t know for sure if this is the proper way to do it, but all I had to do was enter console.log, either square or power, and then the parameters I wanted.

Thank you!

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