<h1>JavaScript预定义类</h1> 

ab+数字+任意字符

ab[0-9][^\r\n]      等价于  ab\d.

'@123@abc@'.replace(/@./g,'Q')      Q23Qbc@             将“@加任意字符”替换为“Q”


'@123@abc@'.replace(/^@./g,'Q')      Q23@abc@           将“以@加任意字符开头的”替换为“Q”


'@123@abc@'.replace(/.@$/g,'Q')      @123@abQ           将“以任意字符加@结束的”替换为“Q”

标识符m

var mulSrt = "@123\n@456\n@789"

mulSrt
     "@123
     @456
     @789
     "
mulSrt.replace(/@\d/g, "X")
     "X23
     X56
     X89 "
mulSrt.replace(/^@\d/g, "X")
     "X23
      @456
      @789 "
mulSrt.replace(/^@\d/gm, "X")
      "X23
       X56
       X89 "

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