Test1：顺序读取速读
var timeArray1 = [];
var timeArray2 = [];
function check1(){
var array = new Uint8ClampedArray(5000000);
for(var i = array.length; i--;){
array[i] = Math.floor(Math.random() * 100);
}
var temp;
var time1 = (new Date()).getTime();
for(var i = array.length; i--;){
temp = array[i];
}
var time2 = (new Date()).getTime();
console.log(time2 - time1);
timeArray1.push(time2 - time1);
}
function check2(){
var array2 = new Array(5000000);
for(var i = array2.length; i--;){
array2[i] = Math.floor(Math.random() * 100);
}
var temp;
var time3 = (new Date()).getTime();
for(var i = array2.length; i--;){
temp = array2[i];
}
var time4 = (new Date()).getTime();
console.log(time4 - time3);
timeArray2.push(time4 - time3);
}
function timer(__fun, __time, __callback){
var now = 0;
function begin(){
var timeout = setTimeout(function(){
if(now !== __time){
now++;
__fun();
begin();
}else{
if(timeArray1.length && timeArray2.length){
console.log("timeArray1 == " + timeArray1 + ", average == " + average(timeArray1));
console.log("timeArray2 == " + timeArray2 + ", average == " + average(timeArray2));
}
__callback && __callback();
}
}, 100);
}
begin();
}
function average(__array){
var total = 0;
for(var i = __array.length; i--;){
total += __array[i];
}
return (total / __array.length);
}
timer(check1, 10, function(){
timer(check2, 10);
});
可见Uint8ClampedArray的读取速度明显比Array要快（条状柱越长，代表花费时间越多）。
Test2：随机读取
//……
function check1(){
var array = new Uint8ClampedArray(5000000);
for(var i = array.length; i--;){
array[i] = Math.floor(Math.random() * 100);
}
var temp;
var time1 = (new Date()).getTime();
for(var i = array.length; i--;){
temp = array[Math.floor(Math.random() * 5000000)];
}
var time2 = (new Date()).getTime();
console.log(time2 - time1);
timeArray1.push(time2 - time1);
}
function check2(){
var array2 = new Array(5000000);
for(var i = array2.length; i--;){
array2[i] = Math.floor(Math.random() * 100);
}
var temp;
var time3 = (new Date()).getTime();
for(var i = array2.length; i--;){
temp = array2[Math.floor(Math.random() * 5000000)];
}
var time4 = (new Date()).getTime();
console.log(time4 - time3);
timeArray2.push(time4 - time3);
}
//……
