Can you determine if a value is numeric without casting it?
For example, how can you differentiate between 'abc' and '123' without converting them to a specific data type?
While visually apparent that 'abc' is not numeric, there are methods like Lodash's _.isNumber(123) that may return unexpected results if the value is not explicitly converted to an integer or number.
Either utilize _.isNaN provided by Lodash library or the standard isNaN function in JavaScript.
_.isNaN(Number("123")) // returns false
_.isNaN(Number("asds")) // returns true
To determine if a given value is a valid number, you can use the following methods:
Number(123) -> will result in a valid number Number("abc") -> will return NaN
You can also achieve the same using unary operators: +123 -> will give you 123 (a valid number) +"abc"- > will be NaN (not a valid number)
See this code snippet for reference:
var number1=123
console.log(Number(number1))
var number2="abc"
console.log(Number(number2))Just wanted to share the different options with you:
In my opinion, using a cast is necessary. However, it can be done without one:
function checkIfNumeric(input) {
return /^\d+$/.test(input)
}
checkIfNumeric('123') // true
checkIfNumeric('abc') // false
This regular expression verifies if every character in the string is a digit. While this works, it's suggested to avoid regex when possible. Opt for casting instead, like other responses have demonstrated:
function checkIfNumeric(input) {
return !isNaN(Number(input))
}
Alternatively:
return !isNaN(+input)
Or, if you want to treat an empty string ('') as non-numeric, simply perform a boolean conversion on the cast instead of using isNaN():
return Boolean(+input)
Another option is:
return !!+input
The decision to use a boolean cast in JavaScript depends on how you plan to utilize the output in your code. In fact, you could just do:
return +input
If you prefer strings starting with digits to be recognized as numeric, you can also employ parseInt().
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