Insert a comma every three digits from right to left.

Window. onloadfunction () {// the whole test is provided by Alucelx vartestFunfunction (callback, str) {vartipElemdocument. createElement (& amp; #39; div & amp; #39;), startTime, duration0; fo... window. onload = function (){
// The entire test is provided by Alucelx
Var testFun = function (callback, str ){
Var tipElem = document. createElement ('div '),
StartTime,
Duration = 0;
For (var j = 5; j> 0; j --){
StartTime = + new Date ();
For (var I = 10000; I> 0; I --){
Callback ();
}
Duration = (+ new Date ()-startTime) + duration;
}
Duration = (duration/5). toFixed (0 );
TipElem. innerHTML = str + 'total time consumed: '+ duration + 'ms ';
Document. body. appendChild (tipElem );
};
 
Var str = '20140901 ';
 
Var cuter1 = function (str) {// with a knife
Var len = str. length,
LastIndex,
Arr = [];
While (len> 0 ){
LastIndex = len;
Len-= 3;
Arr. unshift (str. substring (len, lastIndex ));
}
Return arr. join (',');
};
 
 
Var cuter2 = function (str) {// abcd
Return str. replace (/\ B (? = (? : \ D {3}) + $)/g ,',');
};
 
Var cuter3 = function (str) {// former uncle
Return str. replace (/(. *) (\ d {3}) $/, function (){
If (arguments [1] & arguments [2]) {
Return arguments [1]. replace (/(. *) (\ d {3}) $/, arguments. callee) + "," + arguments [2];
} Else {
Return arguments [0];
}
});
};
 
Var cuter4 = function (str) {// Alucelx
Return str. split (''). reverse (). join (''). replace (/(\ d {3})/g, '$1 ,'). split (''). reverse (). join ('');
};
 
Var cuter5 = function (str) {// situ zhengmei
Var ret = [];
While (str ){
Str = str. replace (/\ d {1, 3} $/g, function (){
Ret. unshift ()
Return ""
});
}
Return ret. join (",");
};
Var cuter6 = function (str) {// situ zhengmei
Var n = str. length % 3;
If (n ){
Return str. slice (0, n) + str. slice (n). replace (/(\ d {3})/g, ', $1 ')
} Else {
Return str. replace (/(\ d {3})/g, ', $ 1'). slice (1)
}
};
Var cuter7 = function (str) {// situ zhengmei
Var ret = ""
For (var I = 0, n = str. length; I <n; I ++ ){
Ret + = str. charAt (I)
If (I % 3 = 0 ){
Ret + = ","
}
}
Return ret
}
 
Var cuter8 = function (str) {// [[valueOf]
Var s2 = []. slice. call (str );
For (var I = s2.length-3; I> 0; I-= 3 ){
S2.splice (I, 0 ,',');
}
Return s2.join ("")
}
Var cuter9 = function (str) {// heard
Var newStr = new Array (str. length + parseInt (str. length/3 ));
NewStr [newStr. length-1] = str [str. length-1];
Var currentIndex = str. length-1;
For (var I = newStr. length-1; I> = 0; I --){
If (newStr. length-I) % 4 = 0)
{
NewStr [I] = ",";
} Else {
NewStr [I] = str [currentIndex --];
}
}
Return newStr. join ("")
}
Var cuter10 = function (str) {// Rekey
Var len = str. length, str2 = '', max = Math. floor (len/3 );
For (var I = 0; I <max; I ++ ){
Var s = str. slice (len-3, len );
Str = str. substr (0, len-3 );
Str2 = (',' + s) + str2;
Len = str. length;
}
Str + = str2;
Return str
}
// The following is a performance test
TestFun (function (){
Cuter1 (str );
}, 'Method 1 ');
 
TestFun (function (){
Cuter2 (str );
}, 'Method 2 ');
 
TestFun (function (){
Cuter3 (str );
}, 'Method 3 ');
 
TestFun (function (){
Cuter4 (str );
}, 'Method 4 ');
 
TestFun (function (){
Cuter5 (str );
}, 'Method 5 ');
TestFun (function (){
Cuter6 (str );
}, 'Method 6 ');
TestFun (function (){
Cuter7 (str );
}, 'Method 7 ');
TestFun (function (){
Cuter8 (str );
}, 'Method 8 ');
TestFun (function (){
Cuter9 (str );
}, 'Method 9 ');
TestFun (function (){
Cuter10 (str );
}, 'Method 10 ');
}

From Ruby's Louvre