正则表达式:javascript key=value 进行字符串拼接，默认不允许逗号出现
/^([a-zA-Z]+=[a-zA-Z0-9]+,)*[a-zA-Z]+=[a-zA-Z0-9]+$/.test('a=a,af=sasfd,b=asdfJH,asa=fdc,c=sdf')
/^([a-zA-Z]+=[a-zA-Z0-9]+,)*[a-zA-Z]+=[a-zA-Z0-9]+$/.test('a=a,af=sasfd,b=asdfJH,asa=fdc,c=sdf')
