js check if string is integer

1// native returns true if the variable does NOT contain a valid number
2isNaN(num)
3
4// can be wrapped for making simple and readable
5function isNumeric(num){
6  return !isNaN(num)
7}
8
9isNumeric(123)         // true
10isNumeric('123')       // true
11isNumeric('1e10000')   // true (This translates to Infinity, which is a number)
12isNumeric('foo')       // false
13isNumeric('10px')      // false

1Number.isInteger(value)
2
3//returns a Boolean

1if (typeof myVar === 'string'){
2    //I am indeed a string
3}

1isNaN(num)         // returns true if the variable does NOT contain a valid number
2
3isNaN(123)         // false
4isNaN('123')       // false
5isNaN('1e10000')   // false (This translates to Infinity, which is a number)
6isNaN('foo')       // true
7isNaN('10px')      // true

1// The Number.isInteger() checks to see if the passed value is an integer
2// Returns true or false
3
4Number.isInteger(2); //True
5Number.isInteger(90); //True
6Number.isInteger("37"); //False
7Number.isInteger(false); //false

1function isInt(str) {
2  return !isNaN(str) && Number.isInteger(parseFloat(str));
3}