JavaScript 中的双倍以上符号

Double more-than symbol in JavaScript

提问by bcm

What does this: >> mean in JavaScript?

这是什么：>> 在 JavaScript 中是什么意思？

Seen in this context:

在这种情况下看到：

document.onkeydown = document.onkeyup = function(e,v,y,k) {
  (i=e.keyCode-37)>>2 || (keys[i] = e.type[5]&&1||(0))
}

采纳答案by amosrivera

Javascript Bitwise Operators

Javascript 按位运算符

Left shift a << b Shifts a in binary representation b (< 32) bits to the left, shifting in zeros from the right.

Sign-propagating right shift a >> b Shifts a in binary representation b (< 32) bits to the right, discarding bits shifted off.

左移 a << b 将二进制表示中的 a 向左移动 b (< 32) 位，从右移零。

符号传播右移 a >> b 将二进制表示中的 a 右移 b (< 32) 位，丢弃移出的位。

回答by M?rten Wikstr?m

>>is the bitwise right shift operator.

>>是按位右移运算符。

For example: 4 >> 1equals 2because 4 is 100in binary notation, which is shifted one bit to the right, giving us 10= 2

例如：4 >> 1等于，2因为 4 是100二进制表示法，它向右移动一位，给我们10=2

回答by Phssthpok

(i=e.keyCode-37)>>2

This code is discarding the two least significant bits of i (similar to dividing by 4), and comparing the result to zero. This will be false when the key pressed is 37-40 (arrow keys), and true otherwise.

此代码丢弃 i 的两个最低有效位（类似于除以 4），并将结果与​​零进行比较。当按下的键为 37-40（箭头键）时，这将是假的，否则为真。

回答by Jim Davis

It's the Bitwise shift operator (see here).

它是按位移位运算符（请参阅此处）。

Now, as to exactly what it's doing here I'm not sure... I'm sure some of our larger-brained bretheren that actually finished college could help us out with that. ;^)

现在，至于它到底在做什么，我不确定……我敢肯定，我们一些真正完成大学学业的大脑袋弟兄可以帮助我们解决这个问题。;^)