JS理论--正则表达式RegExp的创建、元字符、优先度、方法（test(),exec(),match(),replace()）

实战，参数可以对照上面的，代码一定要敲

		var str = 'abc123cba456aaa789';
		var reg = /d+/g;
		
		console.log(reg.test(str)) //str满足匹配表达式返回true
		str2 = 'asdsadasd'
		console.log(reg.test(str2)) //str2不满足匹配表达式返回flase
		
		console.log(reg.exec(str)) //返回数组['123','input':'abc123cba456aaa789']		
		console.log(reg.lastIndex) //返回匹配的位置0
		console.log(reg.exec(str)) //返回数组['456','input':'abc123cba456aaa789']
		console.log(reg.lastIndex) //返回匹配的位置1
		var reg2 = /w(d+)/g
		//下面返回数组['c123','123','input':'abc123cba456aaa789']，包含分组内容
		console.log(reg.exec(str)) 
		
		console.log(str.match(reg)) //返回数组['123','456','789']
		
		console.log(str.replace(reg,"Q")) //返回'abcQcbaQaaaQ'
		console.log(str.replace(reg,function(){
			console.log(arguments)
			return "Q"
			//返回['123',3,'abc123cba456aaa789']和
			//['456',9,'abc123cba456aaa789']和
			//['789',15,'abc123cba456aaa789']
		})) //输出'abcQcbaQaaaQ'