var someText="web2.0 .net2.0";
var pattern=/(\w+)(\d)\.(\d)/g;
var outCome_exec=pattern.exec(someText);
var outCome_matc=someText.match(pattern);

What is outCome_exec[1] and outCome_matc[1]? 

Choice A: true 
Choice B: false 
Choice C: null 
Choice D: Web 
Choice E: Web2.0 
Choice F: undefined
Choice G: net2.0
 
思考1分钟ing........

var str= "ahi" ;
var exp=/a(hi)/;
 
var arr1 = exp.exec(str);
var arr2 = str.match(exp);
alert(arr1);//结果：arr1.length==2;arr1[0]==ahi;arr1[1]==hi;
alert(arr2);//结果：arr2.length==2;arr2[0]==ahi;arr1[1]==hi;结果同上 

function RegExpTest() {
    var src = "The rain in Spain falls mainly in the plain.";
    var re = /(\w+)/g; // 创建正则表达式模式。    
    var arr;
    while ((arr = re.exec(src)) != null){
     document.write(arr.index + "-" + RegExp.lastIndex + "\t" + arr[0]);
     //此处RegExp.lastIndex和arr.lastIndex均有同样的属性，可以互换。在此注意IE6和7的lastIndex重设置0的bug
 
    }
};
 
RegExpTest();
 
//以上例子可以遍历所匹配的内容。并可得到每个小匹配的index和lastIndex；

var src = "The rain in Spain falls mainly in the plain.";
    var re = /(\w+)/g; // 创建正则表达式模式。   
    var arr;
    arr = re.exec(src);    
    RegExp.lastIndex = 0;
    RegExp.index = 0;
    arr.lastIndex = 0;
    arr.index = 0;
 
    document.write(arr.index + "-" + arr.lastIndex + "\t" + arr[0]+"**********"+RegExp.index + "-"
+ RegExp.lastIndex + "\t" + arr[0]);
 
    //结果为0-0 The**********0-3 The。

var src = "The rain in Spain falls mainly in the plain.";
var re = /(\w+)/g; // 创建正则表达式模式。 
var arr;
arr = re.exec(src); 
RegExp.lastIndex = 0;
RegExp.index = 0;
arr.lastIndex = 0;
arr.index = 0;
 
document.write(arr.index + "-" + arr.lastIndex + "\t" + arr[0]+"**********"+RegExp.index + "-"
 + RegExp.lastIndex + "\t" + arr[0]);
//执行第二次arr的index属性会被更新，其实是RegExp对象实例在执行exec方法时，更新全局的RegExp.index和arr的index等，
在后边会介绍
 
arr = re.exec(src);
document.write("
"+arr.index + "-" + arr.lastIndex + "\t" + arr[0]+"**********"+RegExp.index + "-" + RegExp.lastIndex + "\t" + arr[0]);
 
//0-0 The**********0-3 The
//4-8 rain**********4-8 rain

    var src = "The rain in Spain falls mainly in the plain.";
       
    var re1 = /(\w+)/; // 创建正则表达式模式。 
    var re2 = /(\w+)/g; // 创建正则表达式模式。 
    var arr;
 
    arr = re1.exec(src);    
    document.write("R1第一次执行exec:"+RegExp.index + "-" + RegExp.lastIndex + "\t" + arr[0]);
    
    arr = re2.exec(src);
    document.write("
R2第一次执行exec:"+RegExp.index + "-" + RegExp.lastIndex + "\t" + arr[0]);
    
    arr = re1.exec(src);
    document.write("
R1第二次执行exec:"+RegExp.index + "-" + RegExp.lastIndex + "\t" + arr[0]);
 
    arr = re2.exec(src);
    document.write("
R2第二次执行exec:"+RegExp.index + "-" + RegExp.lastIndex + "\t" + arr[0]);  

var src = "The rain in Spain falls mainly in the plain.";
var re = /\w+/g; //有g属性。 
var i = 0;
while (i++<10){
    arr = src.match(re);
    document.write(RegExp.index + "-" + RegExp.lastIndex + "\t" + arr + "
");
 
}
 

//结果如下：
 
38-43 The,rain,in,Spain,falls,mainly,in,the,plain
38-43 The,rain,in,Spain,falls,mainly,in,the,plain
38-43 The,rain,in,Spain,falls,mainly,in,the,plain
38-43 The,rain,in,Spain,falls,mainly,in,the,plain
38-43 The,rain,in,Spain,falls,mainly,in,the,plain
38-43 The,rain,in,Spain,falls,mainly,in,the,plain
38-43 The,rain,in,Spain,falls,mainly,in,the,plain
38-43 The,rain,in,Spain,falls,mainly,in,the,plain
38-43 The,rain,in,Spain,falls,mainly,in,the,plain
38-43 The,rain,in,Spain,falls,mainly,in,the,plain

var src = "The rain in Spain falls mainly in the plain.";
var re = /\w+/; // 无g属性。 
var i = 0;
while (i++<10){
    arr = src.match(re);
    document.write(RegExp.index + "-" + RegExp.lastIndex + "\t" + arr + "
");
 
}
//结果如下：
 
0-3 The
0-3 The
0-3 The
0-3 The
0-3 The
0-3 The
0-3 The
0-3 The
0-3 The
0-3 The  

var src = "The rain in Spain falls mainly in the plain.";
var re = /\w+/g; 
var i = 0;
arr = src.match(re);
while (arr[i]!=null){
    document.write(RegExp.index + "-" + RegExp.lastIndex + "\t" + arr[i] + "
");
    i++;
} 
//结果如下：
 
38-43 The
38-43 rain
38-43 in
38-43 Spain
38-43 falls
38-43 mainly
38-43 in
38-43 the
38-43 plain