Functions - Reading Assignment

[Rasselas_Wildcat]

• How can you create a function in Javascript?
  By using the word ‘function’ followed by the function name we give and parenthesis, example: function mainID(). We can also specify parameters inside the parenthesis: function mainID(name, age). The action will follow, for example: function(name, age) {document.write(mainID)}
• What is the difference between var and let in regards to scope?
  var allows us to define a variable visible to the entire script, let allows us to define a value visible to the specific block only.
• What is a pure function?
  A function that returns a value that is determined only by it’s input value. This function does not return any side effects.

[Lukasz]

• How can you create a function in Javascript?

Starting from keyword function we adding set of parameters and body which
contains the statements that are to be executed when the function is called.

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

While variables declared with var keyword are initialized with undefined before the code is run which means they are accessible in their enclosing scope even before they are declared.

Let variables are not initialized until their definition is evaluated. Variable said to be in “temporal dead zone” from the start of the block until the initialization is processed.

• What is a pure function?

A pure function not only has no side effects but also doesn’t rely on side effects from other code. When called with the same arguments, it always produces the same value and doesn’t do anything else.

[Bunbo_Hue]

Makes sense! Thanks!

[Tor]

1.How can you create a function in Javascript?
Using the key word function staring and finishing the function with curly brackets
2.What is the difference between var and let in regards to scope?
var is global in scope. Let has “block scope”.
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—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).

[Malik]

Excellent answer sir,

Wanted to clear out one small confusion in this statement.

@Tor

var is global in scope. Let has “block scope”.

Var is not always global scoped. When defined in a function, it becomes scoped to the function. However if it’s not written in any function, it becomes globally scoped.

Please reach out if you have any questions.

Happy learning

[Flaflaflohi]

1. You use the “function” keyword followed by the name of the function. You then specify the argument names that the function will accept. You can then create a list of statements that the function will execute using the argument inputs and specify a value that the function will return.

2. The scope of “let” is within the block, whereas the scope of “var” is throughout the program.

3. A pure function is a function that will always return the same value when given the same arguments and do not have side effects.

[mamba]

How can you create a function in Javascript?

• Functions are the bread and butter of JavaScript programming.

• The concept of wrapping a piece of program in a value has many uses, it gives us a way to structure larger programs, to reduce repetition, to associate names with subprograms, and to isolate these subprograms from each other.

• The most obvious application of functions is defining new vocabulary.

• A function definition is a regular binding where the value of the binding is a function.

• 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.

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

• Each binding has a scope, which is the part of the program in which the binding is visible.

• For bindings defined outside of any function or block, the scope is the whole program — you can refer to such bindings wherever you want (called global ).

• Bindings created for function parameters or declared inside a function can be reference only in that function, so they are known as local bindings.

• Every time the function is called, new instances of these bindings are created.

• Bindings declared with “let” and “const” 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.

• Var is always a global scope even if you define the binding inside a function.

• Let is used to set either a global or local scope binding.

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.

• They are completely independent of outside state, do not alter any external states, easy to move around and reuse throughout a program, and great for future adaptations,

[TommyAces]

1. How can you create a function in Javascript?
Function starts with the keyword “function”, the function will have a set of parameters and a body which tells it what to execute when the function is called.
2. What is the difference between var and let in regards to scope?
var is global and let is local
3. What is a pure function?
A pure function is a function with no side effects and doesn’t rely on other code for side effects

[DFig]

1. A function is defined with the function keyword, then a name, followed by parentheses (). Example: function name(parameter1) {code to be executed}

2. A var is global and a let is limited to the block it is within.

3. It provides the same output always and does not have side effects. It also doesn’t rely on side effects from other codes.

[ivo]

1. Function is created with an expression that starts with the key word function. Functions have a set of parameters and body, which contains the statements that are to be executed when the function is called.

2. Bindings declared with let and const 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 can not see it. Var is an old style binding, which are visible through out the whole function that they appear in.

3. 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 property that when called with the same arguments, it always produce the same value.

[Amjak]

1. a function is created with an expression the starts with the keyword function.

2. var are visibile throughout the whole function they appear in, or throughout the global scope if they are not in a function. while let is local to the block/loop that it is declared in, meaning the code before or after the block/loop cannot see it.

3. a pure function is a specific type of value producing function that not only has no side effect but also doesn’t rely on side effects from other code. such a funcion can be substituted by its return value without changing the meaning of the code.

[chakrit]

@ivan

1. How can you create a function in Javascript?
2. What is the difference between var and let in regards to scope?
3. What is a pure function?

1. A function is defined with a function keyword, followed by a name of the function and then followed by a parentheses ().
2. It is different binding visibility in the program. A let is a local binding visible only inside of a block that let is created. It cannot be read before and after a particular statement. The var is global binding which can be seen from elsewhere in the program.
3. A pure function is a function produces a value without any side effect and does not rely on any side effects produced by other code.

[Gabriel_Ng]

@ivan

• How can you create a function in Javascript?
• What is the difference between var and let in regards to scope?
• What is a pure function?

1. Function is a block of code designed to perform a particular task, JavaScript function is defined with the word function, followed by a name, followed by parentheses ()
   function name(parameter1, parameter2, parameter3) {code to be executed}

2. Difference between var and let.
   let: allows to declare the variables in a limited scope to the block, statement, or expression.
   var: allows to declare the variables globally, or locally to an entire function regardless of block scope.

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

[Joyce_Rodriguez]

How can you create a function in Javascript?

The most common way to define a function is to use the keyword “function” followed by a single function name, and the desired parameters, and an instruction block within curly braces.

syntax:

function function_name (parameters)

instructions;

}

Example:

function add () {

var num1 = 5;

var num2 = 8;

sum = num1 + num2;

alert (“The sum is:” + sum);

}

What is the difference between var and let with respect to scope?

The difference is the scope of the variables, it allows to declare variables limiting their scope to the block, declaration, expression where it is being used and var to define a global or local variable in a function regardless of the scope of the block.

What is a pure function?

A pure function is one that, given the same input, always returns the same output value and has no other observable side effect. For example, consider the slice and splice functions of javascript. In functional programming, we avoid functions like splicing that mutate data.

[enrico]

1. How can you create a function in Javascript?
   To define a function:
   function f(x) {BODY}

To assign a function to a binding
f = function (x) {BODY}
let f = x => BODY

2. What is the difference between var and let in regards to scope?
   When defining a variable with VAR it is visible in all the function or even globally in all the program.
   When using LET the variable is visible only inside the block (like if, for etc.)

3. What is 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.

[transylvaniabtc]

1. A function is created with an expression that starts with the keyword function follow by a set of parameters and a body , which contains the statements.
2. let and const are in fact local to the block, var keyword, are visible throughout the whole function that they appear in—or throughout the global scope.
3. A pure function is a specific kind of value-producing function that has no side effects and doesn’t rely on side effects from other code.

[Fati]

1. Functions are created by the keyword function, parenthesis to place parameters in and bracket for statements to be executed.

2. var’s scope is global and can be seen throughout function. let is local to the block it’s in. So if let is declared in a loop, it is not visible to code before or after loop.

3. Pure functions are value producing functions with no side-effects. They do not rely on other code’s values. Pure functions always produce the same value when the same arguments are called.

[jonsax]

@ivan

• How can you create a function in Javascript?
• What is the difference between var and let in regards to scope?
• What is a pure function?

const function = function(a){
};

function funtion(n){
   function code
}

let y = x => x * x

var can be either local or global depending on where it’s placed, whereas let is only locally used inside function statements.

a pure function will execute the same every time regardless of environmental context, whereas an impure function will take information from the global environment and that will determine it’s outcome.

[Crypto_James]

1. How can you create a function in Javascript?
A function is created with an expression that starts with the word function. Functions may or may not have set parameters.

2. What is the difference between var and let in regards to scope?
let gives you the privilege to declare variables that are limited in scope to the block, statement of expression unlike var .
var is rather a keyword which defines a variable globally regardless of block scope.

3. What is a pure function?
A function must pass two tests to be considered “pure”:
1. Same inputs always return same outputs
2. No side-effects

[JamieGoh]

Answers:

1. A function can be created by first naming a function. for example function ‘doubling’. In this case, doubling becomes the name of the function which we will need to assign a parameter to it > function doubling ‘num’. Now doubling takes one parameter called ‘num’.

Now we need a statement which has to be wrap in {} to perform the function task > { return num * num;}

Result will be the statement returns will specifies the value of num multiply by itself.

2. Following in how a function is define, we require statement which wrap in {} to perform the function. Hence, var is specify outside the {} which set a precedent in a global level and let is specify within the {} which affect the function only. However var will always overwrite let in any aspect.

3. Pure functions are functions that accept an input and returns a value without modifying any data outside its scope (Side Effects). Its output or return value must depend on the input/arguments and pure functions must return a value.