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Question

我的问题是为什么myFunction2立即被触发，javascript如何工作？感谢。

<!--when passing "myFunction1" without (), myFunction1 is triggered after 3 seconds as expected-->
<button onclick="setTimeout(myFunction1, 3000);">Try it 1</button>

<script>
function myFunction1() {
    alert('Hello');
}
</script>

<!--when passing "myFunction2" with (), myFunction1 is triggered right away as clicking the button-->
<button onclick="setTimeout(myFunction2(), 3000);">Try it 2</button>

<script>
function myFunction2() {
    alert('Hello');
} 
</script>