What is JavaScript NaN?
JavaScript NaN, which stands for Not a Number, is a special numeric value used to indicate an error condition in a mathematical computation. NaN is a property of the global object in JavaScript that can be used to test any value to check if it is a number or not. When the value is not a number, NaN is returned. This can be useful when parsing values from strings or other non-numeric sources.
How to Check if a Value is NaN
The easiest way to check if a value is NaN is to use the JavaScript global isNaN() function. This function returns true if the value is NaN, and false otherwise. For example:
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var myVal = 'Hello';
alert(isNaN(myVal)); // true
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In the above example, we created a variable called myVal and set it to the string ‘Hello’. We then used the isNaN() function to check if it was a number and it returned true, indicating that the value was NaN.
What Causes NaN?
JavaScript NaN can be caused by a variety of different things. One of the most common causes is attempting to perform an operation on a value that is not a number. For example, if you try to multiply a string by a number, you will get NaN:
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var myVal = 'Hello';
var result = myVal * 10;
alert(result); // NaN
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Another common cause of NaN is attempting to perform a mathematical operation on an empty string. For example, if you try to add an empty string to a number, you will get NaN:
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var myVal = '';
var result = myVal + 10;
alert(result); // NaN
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How to Handle NaN
NaN can be difficult to handle in some cases, but there are a few techniques you can use to make it easier. The first is to always use the isNaN() function to check if a value is a number before attempting to perform any operations on it. This will prevent any unexpected errors from occurring. The second is to use the Number() function to attempt to convert any non-numeric values to numbers before performing operations on them. This will prevent NaN from being returned.
Conclusion
JavaScript NaN is an error condition that can occur when attempting to perform mathematical operations on non-numeric values. It is important to always check for NaN before attempting to perform any operations on a value to prevent unexpected errors from occurring. The isNaN() and Number() functions can be used to check for and convert non-numeric values to numbers.
