JS正则表达式修饰符global(/g)用法分析

var str = "123#abc";
var noglobal = /abc/i;//非全局匹配模式
console.log(re.test(str)); //输出ture
console.log(re.test(str)); //输出ture
console.log(re.test(str)); //输出ture
console.log(re.test(str)); //输出ture
var re = /abc/ig;//全局匹配
console.log(re.test(str)); //输出ture
console.log(re.test(str)); //输出false
console.log(re.test(str)); //输出ture
console.log(re.test(str)); //输出false

var str = "012345678901234567890123456789";
var re = /123/g;
console.log(re.lastIndex); //输出0,正则表达式刚开始创建
console.log(re.test(str)); //输出ture
console.log(re.lastIndex); //输出4
console.log(re.test(str)); //输出true
console.log(re.lastIndex); //输出14
console.log(re.test(str)); //输出ture
console.log(re.lastIndex); //输出24
console.log(re.test(str)); //输出false
console.log(re.lastIndex); //输出0,没有找到匹配项被重置

var str = "012345678901234567890123456789";
var re = /abc/;
//exec没有找到匹配
console.log(re.exec(str));//null
console.log(re.lastIndex);//0

var str = "012345678901234567890123456789";
var re = /123/;
var resultArray = re.exec(str);
console.log(resultArray[0]);//匹配结果123
console.log(resultArray.input);//目标字符串str
console.log(resultArray.index);//匹配结果在原始字符串str中的索引

var str = "012345678901234567890123456789";
var re = /123/;
var globalre = /123/g;
//非全局匹配
var resultArray = re.exec(str);
console.log(resultArray[0]);//输出123
console.log(resultArray.index);//输出1
console.log(globalre.lastIndex);//输出0
var resultArray = re.exec(str);
console.log(resultArray[0]);//输出123
console.log(resultArray.index);//输出1
console.log(globalre.lastIndex);//输出0
//全局匹配
var resultArray = globalre.exec(str);
console.log(resultArray[0]);//输出123
console.log(resultArray.index);//输出1
console.log(globalre.lastIndex);//输出4
var resultArray = globalre.exec(str);
console.log(resultArray[0]);//输出123
console.log(resultArray.index);//输出11
console.log(globalre.lastIndex);//输出14

var str = "012345678901234567890123456789";
var globalre = /123/g;
//循环遍历,获取所有匹配
var result = null;
while ((result = globalre.exec(str)) != null)
{
 console.log(result[0]);
 console.log(globalre.lastIndex);
}