What does the >> symbol mean? On this page, there’s a line that looks like this:
var i = 0, l = this.length >> 0, curr;
What does the >> symbol mean? On this page , there’s a line that
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What does the >> symbol mean? On this page, there’s a line that looks like this:
var i = 0, l = this.length >> 0, curr;
It’s bitwise shifting.
Let’s take the number 7, which in binary is
0b000001117 << 1shifts it one bit to the left, giving you0b00001110, which is 14Similarly, you can shift to the right:
7 >> 1will cut off the last bit, giving you0b00000011which is 3.[Edit]
In JavaScript, numbers are stored as floats. However, when shifting you need integer values, so using bit shifting on JavaScript values will convert it from float to integer.
In JavaScript, shifting by 0 bits will round the number down* (integer rounding) (Better phrased: it will convert the value to integer)
*: Unless the number is negative.
Sidenote: since JavaScript’s integers are 32-bit, avoid using bitwise shifts unless you’re absolutely sure that you’re not going to use large numbers.
[Edit 2]
this.length >> 0will also make a copy of the number, instead of taking a reference to it. Although I have no idea why anyone would want that.