redeclaring-global-properties.js

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// |reftest| skip-if(!xulRuntime.shell) -- needs evaluate

// Any copyright is dedicated to the Public Domain.

// http://creativecommons.org/licenses/publicdomain/

// Attempting to lexically redefine a var is a syntax error.

evaluate("var a;");

assertThrowsInstanceOf(() => evaluate("let a;"), SyntaxError);

// Attempting to lexically redefine a configurable global property that's not a

// var is okay.

this.b = 42;

assertEq(b, 42);

evaluate("let b = 17;");

assertEq(b, 17);

// Attempting to lexically redefine a configurable global property that wasn't

// a var initially but was later declared as one, isn't okay.

this.c = 8675309;

assertEq(c, 8675309);

evaluate("var c;");

assertThrowsInstanceOf(() => evaluate("let c;"), SyntaxError);

// Attempting to lexically redefine a var added by eval code isn't okay.

assertEq(typeof d, "undefined");

eval("var d = 33;");

assertEq(d, 33);

assertThrowsInstanceOf(() => evaluate("let d;"), SyntaxError);

// Attempting to lexically redefine a var added by eval code, then deleted *as a

// name*, is okay.  (The |var| will add the name to the global environment

// record's [[VarNames]], but deletion will go through the global environment

// record's DeleteBinding and so will remove it.)

assertEq(typeof e, "undefined");

eval("var e = 'ohia';");

assertEq(e, "ohia");

delete e;

assertEq(this.hasOwnProperty("e"), false);

evaluate("let e = 3.141592654;");

assertEq(e, 3.141592654);

// Attempting to lexically redefine a var added by eval code, then deleted *as a

// property*, isn't okay.  (Deletion by property doesn't go through the global

// environment record's DeleteBinding algorithm, and so the name isn't removed

// from [[VarNames]].)  And it remains non-okay even if the var is subsequently

// deleted as a name, because if the property doesn't exist, it's not removed

// from [[VarNames]].  But if we add the global property again and then delete

// by name, it *will* get removed from [[VarNames]].

assertEq(typeof f, "undefined");

eval("var f = 8675309;");

assertEq(f, 8675309);

delete this.f;

assertEq(this.hasOwnProperty("f"), false);

assertThrowsInstanceOf(() => evaluate("let f;"), SyntaxError);

delete f;

assertThrowsInstanceOf(() => evaluate("let f;"), SyntaxError);

this.f = 999;

assertThrowsInstanceOf(() => evaluate("let f;"), SyntaxError);

delete f;

evaluate("let f;");

if (typeof reportCompare === "function")

  reportCompare(true, true);

print("Tests complete");