short-circuit-compound-assignment-property-key-evaluation.js

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// Test that property keys are only evaluated once.

class PropertyKey {

  constructor(key) {

    this.key = key;

    this.count = 0;

  toString() {

    this.count++;

    return this.key;

  valueOf() {

    throw new Error("unexpected valueOf call");

// AndAssignExpr

  let obj = {p: true};

  let pk = new PropertyKey("p");

  obj[pk] &&= false;

  assertEq(obj.p, false);

  assertEq(pk.count, 1);

  obj[pk] &&= true;

  assertEq(obj.p, false);

  assertEq(pk.count, 2);

// OrAssignExpr

  let obj = {p: false};

  let pk = new PropertyKey("p");

  obj[pk] ||= true;

  assertEq(obj.p, true);

  assertEq(pk.count, 1);

  obj[pk] ||= false;

  assertEq(obj.p, true);

  assertEq(pk.count, 2);

// CoalesceAssignExpr

  let obj = {p: null};

  let pk = new PropertyKey("p");

  obj[pk] ??= true;

  assertEq(obj.p, true);

  assertEq(pk.count, 1);

  obj[pk] ??= false;

  assertEq(obj.p, true);

  assertEq(pk.count, 2);

if (typeof reportCompare === "function")

  reportCompare(0, 0);