js里[em_([0-9]*)]g正侧什么意思?匹配形如[em_数字若干]的字符串以下都可以匹配[em_][em_1][em_011][em_1234]用match匹配结果取下标1的可以去到数字部分,如'[em_1234]'.match([em_([2023-02-19JavaScript210