lgcl-nullish-assignment-operator.js

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// Copyright (c) 2020 Ecma International.  All rights reserved.

// This code is governed by the BSD license found in the LICENSE file.

/*---

esid: sec-assignment-operators-runtime-semantics-evaluation

description: Logical Nullish Assignment Operator

info: |

    AssignmentExpression:

      LeftHandSideExpression ??= AssignmentExpression

    1. Let lref be the result of evaluating LeftHandSideExpression.

    2. Let lval be ? GetValue(lref).

    3. If lval is neither undefined nor null, return lval.

    4. Let rref be the result of evaluating AssignmentExpression.

    5. Let rval be ? GetValue(rref).

    6. Perform ? PutValue(lref, rval).

    7. Return rval.

features: [logical-assignment-operators]

---*/

var value = undefined;

assert.sameValue(value ??= 1, 1, "(value ??= 1) === 1; where value = undefined");

value = null;

assert.sameValue(value ??= 1, 1, "(value ??= 1) === 1; where value = null");

value = false;

assert.sameValue(value ??= 1, false, "(value ??= 1) === false; where value = false");

value = 0;

assert.sameValue(value ??= 1, 0, "(value ??= 1) === 0; where value = 0");

value = -0;

assert.sameValue(value ??= 1, -0, "(value ??= 1) === -0; where value = -0");

value = NaN;

assert.sameValue(value ??= 1, NaN, "(value ??= 1) === NaN; where value = NaN");

value = "";

assert.sameValue(value ??= 1, "", '(value ??= 1) === "" where value = ""');

value = true;

assert.sameValue(value ??= 1, true, "(value ??= 1) === true; where value = true");

value = 2;

assert.sameValue(value ??= 1, 2, "(value ??= 1) === 2; where value = 2");

value = "test";

assert.sameValue(value ??= 1, "test", '(value ??= 1) === "test"; where value = "test"');

var sym = Symbol("");

value = sym;

assert.sameValue(value ??= 1, sym, "(value ??= 1) === Symbol(); where value = Symbol()");

var obj = {};

value = obj;

assert.sameValue(value ??= 1, obj, "(value ??= 1) === {}; where value = {}");

reportCompare(0, 0);