var b="abeeee:eeeee:eeeeeab";        console.log(b.match(/e+\:e+/g));//["eeee:eeeee"]贪婪模式，只显示第一个匹配到的        console.log(b.match(/e+?\:e+?/g));//["eeee:e", "eeee:e"]非贪婪模式，从前向后查询        console.log(b.match(/e+\:(?=e+)/g));//["eeee:", "eeeee:"]        console.log(b.match(/e+?\:(?=e+)/g));//["eeee:", "eeeee:"]        console.log(b.match(/(?<=e+)?\:(?=e+)/g));//[":", ":"]        console.log(b.match(/e+?\:(?!e+)/g));//null        console.log(b.match(/(?:e+)?\:(?:e+?)/g));//["eeee:e", "eeee:e"]