Juggling bits in JavaScript
(bitmasks)
What do we need
| - BITWISE OR
& - BITWISE AND
Bitmasks
How it works
Which flags are in the mask?
// FLAG A
var A = 1 // 001// FLAG B
var B = 2 // 010// MASK
var MASK = A | C // 101 {5}
// 001 OR
// 100
// ---
// 101 = 5{10}// FLAG C
var C = 4 // 100// FLAG A?
var inTheMask = MASK & A;
// 101 AND
// 001
// ---
// 001 = 1{10} Truthy!// FLAG B?
var inTheMask = MASK & B;
// 101 AND
// 010
// ---
// 000 = 0{10} Falsy!// FLAG C?
var inTheMask = MASK & C;
// 101 AND
// 100
// ---
// 100 = 4{10} Truthy!function logger() {
this.canSeeErrors = this.groups.ADMIN;
this.canSeeDebugs = this.groups.SUPRUSER | this.groups.ADMIN;
this.canSeeInfos = this.groups.USER | this.groups.SUPRUSER | this.groups.ADMIN;
}
logger.prototype.setUserGroup = function(level) {
this.level = level;
}
logger.prototype.groups = {
USER: 1, // 0001
SUPRUSER: 2, // 0010
ADMIN: 4, // 0100
}
logger.prototype.error = function(errorMessage) {
if (this.canSeeErrors & this.level)
console.log("%cERROR: " + errorMessage, "color: #FF033E; font-weight:bold;");
}
logger.prototype.debug = function(debugMessage) {
if (this.canSeeDebugs & this.level)
console.log("%cDEBUG: " + debugMessage, "color: #0000FF; font-weight:bold;");
}
logger.prototype.info = function(infoMessage) {
if (this.canSeeInfos & this.level)
console.log("%cINFO: " + infoMessage, "color: #C8A2C8; font-weight:bold;");
}
Book recomendation
Juggling with bits in JavaScript short
By Rinat U
