Array.flat(depth) Flatten Nested Array ตาม Depth ที่ระบุ (Default=1) สร้าง Array ใหม่ ไม่ Mutate ต้นฉบับ
ตัวอย่าง
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<meta charset="UTF-8" />
<meta name="viewport" content="width=device-width, initial-scale=1.0" />
<title>Array.flat()</title>
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body { font-family: "Segoe UI", Tahoma, Geneva, Verdana, sans-serif; }
.result, .sample { font-size: 20px; font-weight: 500; }
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<h1>Array.flat() Method</h1>
<div class="sample"><pre>[1,2,3,[4,5],[6,[7,8]]]</pre></div>
<div style="color: green;" class="result">After flat(1): <br></div>
<button class="Btn">CLICK HERE</button>
<h3> Click to flatten array depth 1 </h3>
<script>
let resEle = document.querySelector(".result");
let sampleEle = document.querySelector(".sample");
let arr = [1,2,3,[4,5],[6,[7,8]]];
document.querySelector(".Btn").addEventListener("click", () => {
let flat1 = arr.flat(1);
let flat2 = arr.flat(2);
let flatInfinity = arr.flat(Infinity);
resEle.innerHTML = "flat(1): " + flat1 + "<br>";
resEle.innerHTML += "flat(2): " + flat2 + "<br>";
resEle.innerHTML += "flat(Infinity): " + flatInfinity;
});
</script>
</body>
</html>
คำอธิบาย
flat(1)(Default): [1,2,3,4,5,6,[7,8]]flat(2): [1,2,3,4,5,6,7,8]flat(Infinity): Flatten จนหมด Depth- ไม่ Mutate Array ต้นฉบับ
- Empty Slots:
[1,,2].flat()→[1,2](ถูกลบ)
ผลลัพธ์
flat(1): 1,2,3,4,5,6,7,8 (wait, [6,[7,8]] → 6,[7,8])
flat(1): 1,2,3,4,5,6,[7,8]
flat(2): 1,2,3,4,5,6,7,8
flat(Infinity): 1,2,3,4,5,6,7,8
