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

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

1function isNumeric(num){
2  return !isNaN(num)
3}
4isNumeric("23.33"); //true, checking if string is a number. 

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

1var myString     =  "abc123";
2var otherString  =  "123";
3/* isInterger() checks if an value repersents an int  */
4
5Number.isInteger(myString);    //returns false
6Number.isInteger(otherString); //returns true