Question

How to check if string is a negative integer in JavaScript

Answer 1

function isNegativeInteger(s) {
  if (typeof s !== 'string') {
      return false;
  }

  const n = Number(s);

  if (Number.isInteger(n) && n < 0) {
      return true;
  }

  return false;
}



console.log(isNegativeInteger('0')); 
console.log(isNegativeInteger('1')); 
console.log(isNegativeInteger('-5')); 
console.log(isNegativeInteger('-3.14')); 
console.log(isNegativeInteger('')); 
console.log(isNegativeInteger('abc')); 
console.log(isNegativeInteger(' ')); 




/*
run:

false
false
true
false
false
false
false

*/

 

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