js堆棧溢出錯誤

function prompt() {
            var answer = prompt("What is your name","")
            if (answer) {
                alert("Hello, " + answer + "!");
            }
        }      

提示堆棧溢出。我就納悶了。

function prompttt() {
            var answer = prompt("What is your name","")
            if (answer) {
                alert("Hello, " + answer + "!");
            }
        }      

這樣就ok了。