test/Operators/delete2.js

//-------------------------------------------------------------------------------------------------------
// Copyright (C) Microsoft. All rights reserved.
// Licensed under the MIT license. See LICENSE.txt file in the project root for full license information.
//-------------------------------------------------------------------------------------------------------

function write(v) { WScript.Echo(v + ""); }

var r;

var globalX;
var a = new Array(10);
var o = { x : 1, y : 2 };

// Delete a uninitialized global variable
r = delete globalX;  
write("delete uninitialized variable globalX: " + r);
write("globalX : " + globalX);

var explicitVar = 10;

r = delete explicitVar;
write("delete explicitVar       : " + r);
write("value  explicitVar       : " + explicitVar);

implicitVar = 20;
r = delete implicitVar;
write("delete implicitVar       : " + r);
try {
    write("value  implicitVar       : " + implicitVar);
} catch (e) {
    write("value  implicitVar       : Exception");
}

eval("var explicitVarInEval = 30;")
r = delete explicitVarInEval;
write("delete explicitVarInEval : " + r);
try {
    write("value explicitVarInEval : " + explicitVarInEval);
} catch (e) {
    write("value  explicitVarInEval : Exception");
}

eval("implicitVarInEval = 40;")
r = delete implicitVarInEval;
write("delete implicitVarInEval : " + r);
try {
    write("value implicitVarInEval : " + implicitVarInEval);
} catch (e) {
    write("value  implicitVarInEval : Exception");
}

Array.prototype[2] = 100;
a[1] = 200;

write("a[1] = " + a[1]);
r = delete a[1];
write("delete a[1] : " + r);
write("a[1] = " + a[1]);

write("a[2] = " + a[2]);
r = delete a[2];
write("delete a[2] : " + r);
write("a[2] = " + a[2]);

write("o.x = " + o.x);
r = delete o.x;
write("delete o.x : " + r);
write("o.x = " + o.x);

r = delete o.x;
write("delete o.x (again): " + r);

write("o.z = " + o.z);
r = delete o.z;
write("delete o.z (non existing property): " + r);
write("o.z = " + o.z);