Question

How to check if string is a negative integer in TypeScript

Answer 1

function isNegativeInteger(s : any) : boolean {
    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('-7')); 
console.log(isNegativeInteger('-3.14')); 
console.log(isNegativeInteger('')); 
console.log(isNegativeInteger('pqq')); 
console.log(isNegativeInteger(' ')); 





/*
run:

false
false
true
false
false
false
false

*/

 

70+ SQL courses for beginners and professionals