In Typescript, this shows an error saying isNaN accepts only numeric values
isNaN('9BX46B6A')
and this returns false because parseFloat('9BX46B6A')
evaluates to 9
isNaN(parseFloat('9BX46B6A'))
I can still run with the error showing up in Visual Studio, but I would like to do it the right way.
Currently, I have written this modified function -
static isNaNModified = (inputStr: string) => {
var numericRepr = parseFloat(inputStr);
return isNaN(numericRepr) || numericRepr.toString().length != inputStr.length;
}
The way to convert a string to a number is with Number
, not parseFloat
.
Number('1234') // 1234
Number('9BX9') // NaN
You can also use the unary plus operator if you like shorthand:
+'1234' // 1234
+'9BX9' // NaN
Be careful when checking against NaN (the operator ===
and !==
don't work as expected with NaN
). Use:
isNaN(+maybeNumber) // returns true if NaN, otherwise false