unscopables-getters.js

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// @@unscopables checks can call getters.

// The @@unscopables property itself can be a getter.

let hit1 = 0;

let x = "global x";

let env1 = {

    x: "env1.x",

    get [Symbol.unscopables]() {

        hit1++;

        return {x: true};

};

with (env1)

    assertEq(x, "global x");

assertEq(hit1, 1);

// It can throw; the exception is propagated out.

function Fit() {}

with ({x: 0, get [Symbol.unscopables]() { throw new Fit; }})

    assertThrowsInstanceOf(() => x, Fit);

// Individual properties on the @@unscopables object can have getters.

let hit2 = 0;

let env2 = {

    x: "env2.x",

    [Symbol.unscopables]: {

        get x() {

            hit2++;

            return true;

};

with (env2)

    assertEq(x, "global x");

assertEq(hit2, 1);

// And they can throw.

with ({x: 0, [Symbol.unscopables]: {get x() { throw new Fit; }}})

    assertThrowsInstanceOf(() => x, Fit);

reportCompare(0, 0);