Number vs. String
Question: Is there a way to test whether a particular variable holds a number or a string?
Answer: Yes. To test whether the variable holds a number or a string,
use the typeof operator. If your variable holds a number,
typeof(variable) will return "number".
If it holds a string,
typeof(variable) will return "string".
The following are examples of typeof usage:
typeof(123) // result: "number"
typeof("123") // result: "string"
if (typeof k == "string") { alert('k is a string.') }
if (typeof k == "number") { alert('k is a number.') }
The typeof operator can also help you distinguish between
other data types. Depending on the particular variable's value,
the result of typeof can be one of the following:
"number"
"string"
"boolean"
"function"
"object"
"undefined"
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