为什么javascript替换字符串函数这样做？
"aaa\nbbb\nccc".replace(/.*/gm, ".")
// result = "..\n..\n.." but expected was: ".\n.\n."
"aaa\nbbb\nccc".replace(/^.*/gm, ".")
// result = ".\n.\n." -> OK!!!
"aaa\nbbb\nccc".replace(/.*$/gm, ".")
// result = "..\n..\n.." but expected was: ".\n.\n."
我做错了什么？