Source code
Revision control
Copy as Markdown
Other Tools
// Copyright (C) 2019 Leo Balter. All rights reserved.
// This code is governed by the BSD license found in the LICENSE file.
/*---
description: >
Short circuit can prevent evaluation of the right-side expressions
esid: sec-conditional-operator
info: |
ConditionalExpression :
ShortCircuitExpression
ShortCircuitExpression ? AssignmentExpression : AssignmentExpression
ShortCircuitExpression :
LogicalORExpression
CoalesceExpression
CoalesceExpression :
CoalesceExpressionHead ?? BitwiseORExpression
CoalesceExpressionHead :
CoalesceExpression
BitwiseORExpression
Runtime Semantics: Evaluation
CoalesceExpression:CoalesceExpressionHead??BitwiseORExpression
1. Let lref be the result of evaluating CoalesceExpressionHead.
2. Let lval be ? GetValue(lref).
3. If lval is undefined or null,
a. Let rref be the result of evaluating BitwiseORExpression.
b. Return ? GetValue(rref).
4. Otherwise, return lval.
features: [coalesce-expression]
---*/
var x;
function poison() {
throw new Test262Error('should not evaluate poison');
}
x = undefined;
x = undefined ?? 42 ?? undefined ?? poison();
assert.sameValue(x, 42);
x = undefined;
x = 42 ?? undefined ?? poison();
assert.sameValue(x, 42);
x = undefined;
x = undefined ?? 42 ?? poison();
assert.sameValue(x, 42);
x = undefined;
x = 42 ?? poison();
assert.sameValue(x, 42);
reportCompare(0, 0);