ladybird/Libraries/LibJS/Tests/update-expressions-basic.js

load("test-common.js");

try {
  assertThrowsError(
    () => {
      ++x;
    },
    {
      error: ReferenceError,
      message: "'x' is not defined",
    }
  );

  var n = 0;
  assert(++n === 1);
  assert(n === 1);

  var n = 0;
  assert(n++ === 0);
  assert(n === 1);

  var n = 0;
  assert(--n === -1);
  assert(n === -1);

  var n = 0;
  assert(n-- === 0);
  assert(n === -1);

  var a = [];
  assert(a++ === 0);
  assert(a === 1);

  var b = true;
  assert(b-- === 1);
  assert(b === 0);

  var s = "foo";
  assert(isNaN(++s));
  assert(isNaN(s));

  var s = "foo";
  assert(isNaN(s++));
  assert(isNaN(s));

  var s = "foo";
  assert(isNaN(--s));
  assert(isNaN(s));

  var s = "foo";
  assert(isNaN(s--));
  assert(isNaN(s));

  console.log("PASS");
} catch (e) {
  console.log("FAIL: " + e);
}