Mega Code Archive
Subtraction (-)
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The subtraction operator (-) subtracts the number to the right of the operator from the number on the left.
When either of the operands are strings, an attempt is made to convert the strings to numbers.
For example, the line of code:
var resultOfSub = 25 - 102;
would result in the value -77 being stored in the variable resultOfSub.
<html>
<script language="JavaScript">
<!--
aString = new String("45");
answer = aString - 25;
document.write("answer = (45-25)<br>");
document.write("answer = ",answer);
-->
</script>
</html>
The subtract operator has special rules to deal with the variety of type conversions present in JavaScript:
If the two operands are numbers, perform arithmetic subtract and return the result.
If either number is NaN, the result is NaN.
If Infinity is subtracted from Infinity, the result is NaN.
If –Infinity is subtracted from –Infinity, the result is NaN.
If –Infinity is subtracted from Infinity, the result is Infinity.
If Infinity is subtracted from –Infinity, the result is –Infinity.
If +0 is subtracted from +0, the result is +0.
If –0 is subtracted from +0, the result is –0.
If –0 is subtracted from –0, the result is +0.
If either of the two operands is not a number, the result is NaN.
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