发布于 2017-06-29 10:37:24 | 136 次阅读 | 评论: 0 | 来源: 网友投递
这里有新鲜出炉的Javascript教程,程序狗速度看过来!
JavaScript客户端脚本语言
Javascript 是一种由Netscape的LiveScript发展而来的原型化继承的基于对象的动态类型的区分大小写的客户端脚本语言,主要目的是为了解决服务器端语言,比如Perl,遗留的速度问题,为客户提供更流畅的浏览效果。
String.prototype.sizeAt = function(){
var nLen = 0;
for(var i = 0, end = this.length; i<end; i++){
nLen += this.charCodeAt(i)>128?2:1;
}
return nLen;
};
String.prototype.cutStr = function(n, sCut){
if(this.sizeAt() <= n){
return this;
}
sCut = sCut || "";
var max = n-sCut.sizeAt();
var nLen = 0;
var s = this;
for(var i =0,end = this.length;i<end;i++){
nLen += this.charCodeAt(i)>128?2:1;
if(nLen>max){
s = this.slice(0,i);
s += sCut;
break;
}
}
return s.toString();
};
String.prototype.cutStrButUrl = function(n, sCut){
if(this.sizeAt() <=n){
return this.toString();
}
sCut = sCut || "";
var max = n-sCut.sizeAt();
var s = this;
//查找所有包含的url
var aUrl = s.match(/https?:\/\/[a-zA-Z0-9]+(\.[a-zA-Z0-9]+)+([-_A-Z0-9a-z\$\.\+\!\*\/,:;@&=\?\~\#\%]*)*/gi);
//当第max个字符刚好在url之间时,bCut会被设置为flase;
var bCut = true;
if(aUrl){
//对每个url进行判断
for(var i=0, endI = aUrl.length;i<endI;i++){
var sUrl = aUrl[i];
//可能出现两个相同url的情况
var aP = s.split(sUrl);
var nCurr = 0;
var nLenURL = sUrl.sizeAt();
var sResult = "";
for(j = 0, endJ = aP.length; j<endJ; j++){
nCurr +=aP[j].sizeAt();
sResult +=aP[j];
sResult += sUrl;
//当前字数相加少于max但添加url超过max:即会截到url
if(nCurr < max && nCurr + nLenURL>max){
s = sResult + sCut;
bCut = false;
break;
}
nCurr += nLenURL;
}
if(bCut === false){
break;
}
};
}
if(bCut){
s = s.cutStr(n, sCut);
}
return s.toString();
};
console.log('正常截取20个字符'.cutStrButUrl(20,'......'));
console.log('正常截取20个字符,但我超了'.cutStrButUrl(20,'......'));
console.log('有url的字符串http://www.baidu.com你能截取到吗?'.cutStrButUrl(20,'......'));
console.log('http://www.baidu.com有两个相同url的字符串http://www.baidu.com好吗?'.cutStrButUrl(51, '......'));