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JavaScript: Return true if the given value is a number, false otherwise

JavaScript fundamental (ES6 Syntax): Exercise-105 with Solution

Write a JavaScript program that return true if the given value is a number, false otherwise.

  • Use parseFloat() to try to convert n to a number.
  • Use !Number.isNaN() to check if num is a number.
  • Use Number.isFinite() to check if num is finite.
  • Use Number() and the loose equality operator (==) to check if the coercion holds.

Sample Solution:

JavaScript Code:

//#Source https://bit.ly/2neWfJ2 
const validateNumber = n => !isNaN(parseFloat(n)) && isFinite(n) && Number(n) == n;
console.log(validateNumber('200'));
console.log(validateNumber('10'));
console.log(validateNumber('abc'));

Sample Output:

true
true
false

Pictorial Presentation:

JavaScript Fundamental: Return true if the given value is a number, false otherwise.

Flowchart:

flowchart: Return true if the given value is a number, false otherwise

Live Demo:

See the Pen javascript-basic-exercise-105-1 by w3resource (@w3resource) on CodePen.


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Previous: Write a JavaScript program to test a value, x, against a predicate function. If true, return fn(x). Else, return x.
Next: Write a JavaScript program to create an array of elements, ungrouping the elements in an array produced by zip and applying the provided function.

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JavaScript: Tips of the Day

Chunks an array into n smaller arrays

Example:

const tips_chunkIntoN = (arr, n) => {
  const size = Math.ceil(arr.length / n);
  return Array.from({ length: n }, (v, i) =>
    arr.slice(i * size, i * size + size)
  );
}
console.log(tips_chunkIntoN([1, 2, 3, 4, 5, 6, 7,8], 4));

Output:

[[1,2],[3,4],[5,6],[7,8]]