exp-operator-evaluation-order.js

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// Copyright (C) 2016 Rick Waldron, André Bargull. All rights reserved.

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

/*---

author: Rick Waldron, André Bargull

esid: sec-exp-operator-runtime-semantics-evaluation

description: Exponentiation Operator expression order of evaluation

info: |

    ExponentiationExpression:

      UpdateExpression ** ExponentiationExpression

    1. Let left be the result of evaluating UpdateExpression.

    2. Let leftValue be ? GetValue(left).

    3. Let right be the result of evaluating ExponentiationExpression.

    4. Let rightValue be ? GetValue(right).

    5. Let base be ? ToNumber(leftValue).

    6. Let exponent be ? ToNumber(rightValue).

    7. Return the result of Applying the ** operator with base and exponent as specified in 12.7.3.4.

features: [exponentiation]

---*/

var capture = [];

var leftValue = { valueOf() { capture.push("leftValue"); return 3; }};

var rightValue = { valueOf() { capture.push("rightValue"); return 2; }};

(capture.push("left"), leftValue) ** (capture.push("right"), rightValue);

// Expected per operator evaluation order: "left", "right", "leftValue", "rightValue"

assert.sameValue(capture[0], "left", "Expected the 1st element captured to be 'left'");

assert.sameValue(capture[1], "right", "Expected the 2nd element captured to be 'right'");

assert.sameValue(capture[2], "leftValue", "Expected the 3rd element captured to be 'leftValue'");

assert.sameValue(capture[3], "rightValue", "Expected the 4th element captured to be 'rightValue'");

reportCompare(0, 0);