Page 64 - JavaScript

Chapter 5: Arithmetic (Math)

Remarks

• The clz32 method is not supported in Internet Explorer or Safari

Examples

Addition (+)

The addition operator (+) adds numbers.

var a = 9,
b = 3,
c = a + b;

c will now be 12

This operand can also be used multiple times in a single assignment:

var a = 9,
b = 3,
c = 8,
d = a + b + c;

d will now be 20.

Both operands are converted to primitive types. Then, if either one is a string, they're both
converted to strings and concatenated. Otherwise, they're both converted to numbers and added.

null + null; // 0
null + undefined; // NaN
null + {}; // "null[object Object]"
null + ''; // "null"

If the operands are a string and a number, the number is converted to a string and then they're
concatenated, which may lead to unexpected results when working with strings that look numeric.

"123" + 1; // "1231" (not 124)

If a boolean value is given in place of any of the number values, the boolean value is converted to
a number (0 for false, 1 for true) before the sum is calculated:

true + 1; // 2

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