diff --git a/src/2d.js b/src/2d.js
new file mode 100644
index 0000000..914e658
--- /dev/null
+++ b/src/2d.js
@@ -0,0 +1,85 @@
+function sqr(x) {
+	return x * x;
+}
+
+export class Vec2 {
+	constructor(x, y) {
+		this.x = x || 0;
+		this.y = y || 0;
+	}
+
+	add(y) {
+		return new Vec2(this.x + y.x, this.y + y.y);
+	}
+
+	sub(y) {
+		return new Vec2(this.x - y.x, this.y - y.y);
+	}
+
+	mul(k) {
+		return new Vec2(this.x * k, this.y * k);
+	}
+
+	conj() {
+		return new Vec2(this.x, -this.y);
+	}
+
+	yx() {
+		return new Vec2(this.y, this.x);
+	}
+
+	complexMul(y) {
+		return new Vec2(this.x * y.x - this.y * y.y, this.x * y.y + this.y * y.x);
+	}
+
+	complexInv() {
+		return this.conj().mul(1 / this.norm());
+	}
+
+	complexDiv(y) {
+		return this.complexMul(y.complexInv());
+	}
+
+	addTo(y) {
+		this.x += y.x;
+		this.y += y.y;
+	}
+
+	subTo(y) {
+		this.x -= y.x;
+		this.y -= y.y;
+	}
+
+	mulTo(k) {
+		this.x *= k;
+		this.y *= k;
+	}
+
+	equal(y) {
+		return this.x == y.x && this.y == y.y;
+	}
+
+	arg() {
+		return Math.atan2(this.y, this.x);
+	}
+
+	abs() {
+		return Math.sqrt(this.norm());
+	}
+
+	norm() {
+		return sqr(this.x) + sqr(this.y);
+	}
+
+	clone() {
+		return new Vec2(this.x, this.y);
+	}
+
+	dot(y) {
+		return this.x * y.x + this.y * y.y;
+	}
+
+	cross(y) {
+		return this.x * y.y - this.y * y.x;
+	}
+}
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diff --git a/tests/2d.test.js b/tests/2d.test.js
new file mode 100644
index 0000000..6c603a0
--- /dev/null
+++ b/tests/2d.test.js
@@ -0,0 +1,52 @@
+import assert from 'node:assert';
+import { Vec2 } from '../src/2d.js';
+
+describe('Vec2', function () {
+	it('construct', function() {
+		let p = new Vec2(1, 2);
+		assert.equal(p.x, 1);
+		assert.equal(p.y, 2);
+	});
+
+	it('equal', function() {
+		assert.ok((new Vec2(1, 2)).equal(new Vec2(1, 2)));
+		assert.ok(!(new Vec2(1, 2)).equal(new Vec2(1, 12)));
+	});
+
+	it('vector calculation', function() {
+		let p = new Vec2(2, 4), q = new Vec2(3, 1);
+		assert.ok(p.add(q).equal(new Vec2(5, 5)));
+		assert.ok(p.sub(q).equal(new Vec2(-1, 3)));
+		assert.ok(p.mul(1.5).equal(new Vec2(3, 6)));
+		assert.ok(p.yx().equal(new Vec2(4, 2)));
+	});
+
+	it('vector calculation(TO)', function () {
+		let p = new Vec2(2, 4), q = new Vec2(3, 1);
+		p.addTo(q);
+		assert.ok(p.equal(new Vec2(5, 5)));
+		p.subTo(q);
+		assert.ok(p.equal(new Vec2(2, 4)));
+		p.mulTo(1.5);
+		assert.ok(p.equal(new Vec2(3, 6)));
+	});
+
+	it('abs & norm', function() {
+		let p = new Vec2(3, 4);
+		assert.equal(p.abs(), 5);
+		assert.equal(p.norm(), 25);
+	});
+
+	it('complex calculation', function() {
+		let p = new Vec2(1, 4), q = new Vec2(0, 1);
+		assert.ok(p.complexMul(q).equal(new Vec2(-4, 1)));
+		assert.ok(p.complexDiv(q).equal(new Vec2(4, -1)));
+		assert.equal(q.arg(), Math.PI / 2);
+	});
+
+	it('dot & cross product', function() {
+		let p = new Vec2(2, 4), q = new Vec2(3, 1);
+		assert.equal(p.dot(q), 10);
+		assert.equal(p.cross(q), -10);
+	});
+});
\ No newline at end of file