I was just experimenting and tried putting this in the console:
4 | 2 | 4 | 1 | 10
returns 15 in console..
4 | 2 | 4 | 3 | 1
returns 7 in console..
I tried that on Chrome and Firefox.
Why?
I'm just starting with learning JavaScript... maybe I'm missing a concept here?
The | operator in JavaScript is a bitwise integer OR operator. So it's doing an OR operation on the bits you're giving it, resulting in 15.
A bitwise OR operation takes each bit in the value and sets the corresponding bit in the result if either of the input bits in that position is set. So
4 is 0100 in binary
2 is 0010
4 is 0100
1 is 0001
10 is 1010
----
1111 = 15 decimal
Update: In a comment on your question, you've said you were expecting true rather than 15. If so, you want the logical OR operator, ||, not the bitwise operator, although || may also surprise you with what it returns (4 || 2 || 4 || 1 || 10 = 4, not true), as JavaScript's logical OR (||) is curiously powerful, more so than in many other languages.
| to combine the various file mode flags.
You're using an OR operation
If you want a true/false or, you'll want ||.
|| operator is not going to result in either true or false with those integer operands. Both cases will simply result in 4|| won't give you true or false either.The | operator is the bitwise or operator.
The | operator lines up the binary digits of each operand, and returns 1 for that place if there is a 1 in that place either or both of the operands.
For example, let's look at what 3 | 10 does:
3 is 11 in binary.
10 is 1010 in binary.
Line them up, and you get
3 - 0011
10 - 1010
Result - 1011
The result 1011 is 11 in decimal, so the result of this example is 11.
Here's one of the examples in your question 4 | 2 | 4 | 1 | 10
4 - 0100
2 - 0010
4 - 0100
1 - 0001
10 - 1010
| ======
1111
And 1111 is binary for 15, which was the result you got.
The bitwise or operator, along with other bit manipulation operators are generally used for low-level computations. For example, you can implement arithmetic like multiplication, addition, and division entirely with bitwise operators.
