Comparison Table
| Case | /^\d+$/ .test(variable) | /^[0-9]+$/ .test(variable) | !isNaN (variable) | typeof variable |
|---|---|---|---|---|
| “123” | True | True | True | string |
| ” “ | False | False | True | string |
| 123 | True | True | True | number |
| “1.23” | False | False | True | string |
| 1.23 | False | False | True | number |
| “abc” | False | False | False | string |
- RegexPattern.test(String)
/^[0-9]+$/.test("123")
> True
/^\d+$/.test("123")
> True- isNaN: This function works with both numbers and numbers inside strings.
isNaN(10)
> False
isNaN("10")
> False
isNaN(" ") // Considers blank spaces as a number
> False
isNaN("not a number")
> TrueWhen using isNaN to determine if a string is a number, be careful that this function returns false for an empty string or a string with only spaces in it.
- typeOf : Strictly checks numbers and returns “number” for numeric values.
typeof 10
> "number"
typeof "10"
> "string"Below is the code I used to compare the methods:
var str = "1.23";
var space = " ";
var num = 123;
var float = 1.23;
var letters = "abc";
console.log(/^\d+$/.test(str));
console.log(/^\d+$/.test(space));
console.log(/^\d+$/.test(num));
console.log(/^\d+$/.test(float));
console.log(/^\d+$/.test(letters));
console.log(/^[0-9]+$/.test(str));
console.log(/^[0-9]+$/.test(space));
console.log(/^[0-9]+$/.test(num));
console.log(/^[0-9]+$/.test(float));
console.log(/^[0-9]+$/.test(letters));
console.log(!isNaN(str));
console.log(!isNaN(space));
console.log(!isNaN(num));
console.log(!isNaN(float));
console.log(!isNaN(letters));
console.log(typeof str);
console.log(typeof space);
console.log(typeof num);
console.log(typeof float);
console.log(typeof letters);