event loop

图片可参考 ppt

console.log('Hi')

setTimeout(function cb1() {
    console.log('cb1') // cb 即 callback
}, 5000)

console.log('Bye')

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DOM 事件，也用 event loop

<button id="btn1">提交</button>

<script>
console.log('Hi')

$('#btn1').click(function (e) {
    console.log('button clicked')
})

console.log('Bye')
</script>