function $p(msg){
var ua = navigator.userAgent.toLowerCase();
if( ua.indexOf("firefox") > -1){
console.log(msg);
}else{
alert(msg)
}
}
function StringBuffer () {
this._strings_ = new Array();
}StringBuffer.prototype.append = function(str) {
this._strings_.push(str);
};StringBuffer.prototype.toString = function() {
return this._strings_.join("");
};var d1 = new Date();
var str = "";
for (var i=0; i < 10000; i++) {
str += "text";
}
var d2 = new Date();$p("Concatenation with plus: "
+ (d2.getTime() - d1.getTime()) + " milliseconds");var buffer = new StringBuffer();
d1 = new Date();
for (var i=0; i < 10000; i++) {
buffer.append("text");
}
var result = buffer.toString();
d2 = new Date();$p("<br />Concatenation with StringBuffer: "
+ (d2.getTime() - d1.getTime()) + " milliseconds");我的结果是:Concatenation with plus: 1 millisecondsConcatenation with StringBuffer: 3 milliseconds
问题来了, 大家觉得哪个会更快呢??
w3school 上的说明是推荐 数组的方式, 但为什么我的结果却是累加的方式更快呢??
var ua = navigator.userAgent.toLowerCase();
if( ua.indexOf("firefox") > -1){
console.log(msg);
}else{
alert(msg)
}
}
function StringBuffer () {
this._strings_ = new Array();
}StringBuffer.prototype.append = function(str) {
this._strings_.push(str);
};StringBuffer.prototype.toString = function() {
return this._strings_.join("");
};var d1 = new Date();
var str = "";
for (var i=0; i < 10000; i++) {
str += "text";
}
var d2 = new Date();$p("Concatenation with plus: "
+ (d2.getTime() - d1.getTime()) + " milliseconds");var buffer = new StringBuffer();
d1 = new Date();
for (var i=0; i < 10000; i++) {
buffer.append("text");
}
var result = buffer.toString();
d2 = new Date();$p("<br />Concatenation with StringBuffer: "
+ (d2.getTime() - d1.getTime()) + " milliseconds");我的结果是:Concatenation with plus: 1 millisecondsConcatenation with StringBuffer: 3 milliseconds
问题来了, 大家觉得哪个会更快呢??
w3school 上的说明是推荐 数组的方式, 但为什么我的结果却是累加的方式更快呢??
var buffer = [];
d1 = new Date();
for (var i = 0; i < 10000; i++) {
buffer.push("text");
}
var result = buffer.join('');
Concatenation with plus: 3 milliseconds 这个是累加的 Concatenation with StringBuffer: 38 milliseconds 这个是数组的 ....
function $p(msg){var ua = navigator.userAgent.toLowerCase();
if( ua.indexOf("firefox") > -1){
console.log(msg);
}else{
alert(msg)
}} var d1 = new Date();
var str = "";
for (var i=0; i < 10000; i++) {
str += "text";
}
var d2 = new Date();$p("Concatenation with plus: "
+ (d2.getTime() - d1.getTime()) + " milliseconds");var buffer = [];
d1 = new Date();
for (var i=0; i < 10000; i++) {
buffer.push("text");
}
var result = buffer.join('');
d2 = new Date();$p("<br />Concatenation with StringBuffer: "
+ (d2.getTime() - d1.getTime()) + " milliseconds");
IE6 下 94 ms 和 15ms
FF 下 都是 1ms