How to convert number to string in JavaScript when user inputs a number

Question

let num = prompt("enter a number");
let foo = num.split("").map(item => parseInt(item, 10));
let fig = [0, 1, 2, 3, 4, 5, 6, 7, 8, 9];
let arr = [
  "zero",
  "one",
  "two",
  "three",
  "four",
  "five",
  "six",
  "seven",
  "eight",
  "nine"
];
fig[0] = arr[0];
fig[1] = arr[1];
fig[2] = arr[2];
// let filteredNum = foo.filter(number => fig.includes(number));
// console.log(filteredNum);
// console.log(fig[0]);
// console.log(fig[1]);
// console.log(fig[2]);

I need help with this, I have an array of numbers (0 - 9). I provided a prompt for a user to input a number, such that that when the user inputs 1, it prints out a string 'one', if the user inputs 34, it prints out string of three four.

Nikhil Aggarwal · Accepted Answer · 2018-05-18 10:12:35Z

2

You can try following

let num = prompt("enter a number");
let foo = num.split("").map(item => parseInt(item, 10));

let arr = ["zero","one","two","three","four","five","six","seven","eight","nine"];

console.log(foo.reduce((a,c) => a + " " + arr[c], ""));

Please see, there is no need of fig as you already have index of arr to match the numeric value of string

edited May 18, 2018 at 10:12

answered May 18, 2018 at 10:02

Nikhil Aggarwal

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11 Comments

Peoray Over a year ago

Thanks, is there any way to check if an alphabet or non-number(special characters) is inputted by the user, an error should be display?

Nikhil Aggarwal Over a year ago

You can check for isNaN() or parseInt() and then check for NaN first. If its NaN, then its invalid and return else continue with logic

Peoray Over a year ago

something like this: if(isNaN(foo)) { }

Nikhil Aggarwal Over a year ago

@Perorary - This one covers all the cases - if(isNaN(parseInt(foo, 10))) { }

Peoray Over a year ago

I'm a little confused what the '10' is doing inside of the parseInt(), can you explain, please?

|

Dan Nagle · Accepted Answer · 2018-05-18 10:24:06Z

0

Do you need to check that the string is a number?

const num = prompt("enter a number");

const arr = [ "zero", "one", "two", "three", "four",
            "five", "six", "seven", "eight", "nine" ];

let foo = [];

if(!isNaN(num)) {
  foo = num.split('').map(n => arr[n]).join(' ');
}

console.log(foo);

answered May 18, 2018 at 10:24

Dan Nagle

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Comments

Faly · Accepted Answer · 2018-05-18 10:05:02Z

0

You can convert your number into string and use an object as a dictionary, :

const num = prompt("enter a number");
const dict = {
  "0": "zero",
  "1": "one",
  "2": "two",
  "3": "three",
  "4": "four",
  "5": "five",
  "6": "six",
  "7": "seven",
  "8": "eight",
  "9": "nine"
}
const res = `${num}`.split('').map(e => dict[e]).join(' ');
console.log(res);

answered May 18, 2018 at 10:05

Faly

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Comments

Ankit Agarwal · Accepted Answer · 2018-05-18 10:06:42Z

0

I don't think reducer is really required here. This is a simple logic and can be achieved using a simple loop too.

let num = prompt("enter a number");
let foo = num.split("").map(item => parseInt(item, 10));

let arr = ["zero","one","two","three","four","five","six","seven","eight","nine"];

var inputStr = '';
foo.forEach((num)=>{
  inputStr +=  arr[num] + ' ';
});
console.log(inputStr);

Or you can even use a one liner like this:

let num = prompt("enter a number");
let arr = ["zero","one","two","three","four","five","six","seven","eight","nine"];

let foo = num.split("").map(item => arr[parseInt(item, 10)]).join(' ');

console.log(foo);

answered May 18, 2018 at 10:06

Ankit Agarwal

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2 Comments

Peoray Over a year ago

I decided to add a '-' to the string but I don't want it to show after the last string. Here is JS fiddle jsfiddle.net/ht3qmb46

Ankit Agarwal Over a year ago

@Peoray stop asking for everything here.

Nina Scholz · Accepted Answer · 2018-05-18 10:17:11Z

0

You could use Array.from for getting single digits (string as an iterable) and map the word if exists. If not take the value.

Later join the array with space.

var numbers = prompt("enter a number"),
    array = ["zero", "one", "two", "three", "four", "five", "six", "seven", "eight", "nine"];

console.log(Array.from(numbers, i => array[i] || i).join(' '));

answered May 18, 2018 at 10:17

Nina Scholz

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Comments

Muhammad Salman · Accepted Answer · 2018-05-18 10:42:05Z

Code :

console.log(prompt("enter a number").split``.map(_ => ~~_).reduce((_, i) => `${_} ${"zero one two three four five six seven eight nine".split` `[i]}`, ``));

Methods :

This uses map and reduce

Explanation :

console.log(                /*begin console.log*/
    prompt(                 /*take input*/
        'enter a number'.   /*input text*/
            split``.        /*split at every single char*/
            map(            /*map over all elements of the array*/
                _ => ~~_).  /*convert to number and reduce to integer*/
                reduce(     /*begin reducing the array to one value*/
                    (_,i)=> /*parameters*/
                    `${_} ${'zero one two three four five six seven eight nine'.split` `[i]}`
                , ''))
// the last part writes value of _ and then creates a string (0-9) and splits at 
//space and then selects the value depending on i

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