Issue with isNumeric

[xogeny]

I'm not sure what is going on in this function:

/**
 * Check if value is a finite number
 * @param {float} n - number to evaluate
 * @returns {boolean} True if n is a finite number
 */
export function isNumeric(n) {
    var isNum = false;
    if (typeof n === "number") {
        var num = parseFloat(n);
        isNum = !isNaN(num);
        if (isNum && !isFinite(num)) {
            throw {
                code: "D1001",
                value: n,
                stack: new Error().stack,
            };
        }
    }
    return isNum;
}

According to the JSDoc, n is presumed to be a number (not a string?). This is substantiated by the typeof n === "number" conditional. While parseFloat can take a number as an argument, what is the point if we know that n is already a number (which we know is the case because of the type check)?

[andrew-coleman]

The JSDoc is wrong here, n could be a value of any type, this function is testing to see if it is a number and in the value space of a JSON number - i.e. not infinity or NaN.

[xogeny]

Sorry, I perhaps buried the lede here. That call to parseFloat seems completely superfluous here. We know (because of the typeof that n is a number. Calling parseFloat with a number just returns the argument (as far as I can tell). So you don't need the variable num here...you could just use n since they should be identical. Or am I missing something?

[andrew-coleman]

Ah yes, good point. I'll remove that.