JavaScript Quiz Part 2

If you want to answer part1 check out part1

1.How to reverse a String Using Reduce Method.

example: if you pass 'king' as an argument output is 'gnik'

2.what is the difference between slice and splice.

3.How to convert an object into a string?

Comments

[Sudeep Pandey]

slice doesn't modify the array and create a new array but splice modified the array

[Sudeep Pandey]

var input = "king";
var reverseString = input.split("").reduce((accumulator, currentValue, index, array)=> currentValue + accumulator);

[Lea Rosema (she/her)]

1. "Hello World".split('').reduce((a, b) => b + a)

2. slice is a prototype function on Array and String. It doesn't mutate and returns a new Array/String that equals to an extract of the Array/String. splice is a prototype function on Array and is used to insert and delete elements at a given index of the array. It mutates the actual array and returns the deleted elements.

3. You can explicitly call obj.toString() or you can use JavaScript's coercion: (obj + ""), so the obj.toString() method is implicitly called to convert it to a string. By default, the output is not too useful; it returns [object Object], but you can override the toString() method. Or, if you want to serialize the object into a string representation, you may want to use JSON.stringify(obj)

[Sai gowtham]

Wow i was expecting this answer for reversing a string you can even do

const stringRev = (str)=>[...str].reduce((acc,e)=>e+acc)

[Florian Reuschel]

1) How to reverse a string using reduce method?

const rev = str => [...str].reduce((carry, char) => char.concat(carry), '')

Specifically, [...str] is superior to str.split('') because it correctly handles Unicode:

'😎'.split('') // ["�", "�"]
[...'😎'] // ["😎"]

2) What is the difference between slice and splice?

slice copies a range out of an array. splice deletes and/or inserts items at a given position in an array.

3) How to convert an object into a string?

The question's a little to broad imo, I'm gonna spare the time writing out exactly what Avalander did.

[jtkohne]

1. First I just want to say why would you ever need to use the reduce method when working with a string when you can just simply do some casting from a string to array the back, especially since all you're trying to do is reverse the string. Since a lot of have already answered the question for the reduce method I offer you these two solutions instead...

"king".split("").reverse().join(""); // result will be "gnik"

You could also accomplish this with a simple loop

var str = "king";
var reversed = "";
var i = str.length-1;
while (i >=0) {
reversed += str[i];
i--;
}
// result in the reversed variable will be "gink"

1. This one is constantly confused across JS developers. Splice actually returns a mutated version of the original array, and in the process actually modifies the array. Slice on the other hand can return a copy or a mutated version of the array, but the original array remains the way it was before the operation was executed. For example, if you try arr.splice(1, 1); it will literally remove a single item from an array starting at index 1. If you were to do the same thing with a slice operation, arr.slice(1, 1) it will start at index 1 and return 1 item in a new array (new array in memory). Splice also is used to manipulate arrays without the need to strore a returned result in a new variable since the original reference in memory is modified, whereas slice is intended to be used as a executable operation on an existing array and a returned value will either get passed as a parameter or stored in memory with it's own pointer and variable name.

2. Avalander's answer is pretty concise, but if I were to give an answer based on how the question is worded it would have to be JSON.stringify(obj);

[YCM Jason]

reverseStr = ss => [ss].reduce(([...ss]) => ss.reverse().join(''));

[Ben Halpern]

Loving these threads, Sai!

[Navneet Sahota]

1.How to reverse a String Using Reduce Method.

function reverseString(str) {
  const arr = str.split('');
  return arr.reduce((acc, val) => val + acc,"");
}

2.What is the difference between slice and splice?

• Slice method is used to get some portion of the existing array/string.
• Splice method actually mutates the existing array and can add or remove items from the array.

3.How to convert an object into a string?

• Not Sure what you want as output. Others have explained it well though.

[ItsASine (Kayla)]

ELI5 version of #2: Slice returns a new array while splice modifies the original reference

[Meghan (she/her)]

// #1
"hello".split("").reduce((c,v,i,a) => c + a[a.length-i-1], "");

#2
// .slice returns a shallow copy of "substring" of elements in an Array
// .splice removes elements from elements at an index and can insert as well

#3
This is a bit of a trick question and depends on what you're looking for, and @avalander went into a lot of detail for this