Wednesday, May 26, 2021

Javascript Practice 62: JS Hero - undefined

 
Question: 

Write a function hello having one parameter and returning 'Hello <parameter>!'. If hello is called without an argument, 'Hello world!' should be returned.

Example: hello('Nala') should return 'Hello Nala!'.




Answer: 

function hello (p) {

if (p === undefined) {
        
return `Hello world!`;

} else {
        
return `Hello ${p}!`}

};




or




function hello (param) {

if (param) {

return 'Hello ' + param + '!' ;

} else { 

return 'Hello world!'}

};




> we declare a function 'hello' 
> it has one parameter - 'p'
> we open if / else statements to check 
>> if the function 'hello' is called with a parameter 'p'
>> or it is called without a parameter
> if it is called with a parameter then we have to return a string 
> this string will append the parameter 'p' to 'Hello' and return it
> in case the function is called without a parameter
> then we should simply return 'Hello world!' 
> we can solve it in many ways
> we have two solutions here
> the first solution checks if the parameter 'p' is undefined
> like this: p === undefined
> if it is undefined then the function will return 'Hello world!' 
> or else it will return `Hello ${p}!`
> the second solution checks if the parameter ' param' exists
> like this (param) 
> if it exists then we get 'Hello ' + param + '!' 
> if it does not exist then we shall be returned 'Hello world!'

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