// Declares a function-scoped variable named `x`, and implicitly assigns the// special value `undefined` to it. Variables without value are automatically// set to undefined.varx;// Variables can be manually set to `undefined` like sovarx2=undefined;// Declares a block-scoped variable named `y`, and implicitly sets it to// `undefined`. The `let` keyword was introduced in ECMAScript 2015.lety;// Declares a block-scoped, un-reassignable variable named `z`, and sets it to// a string literal. The `const` keyword was also introduced in ECMAScript 2015,// and must be explicitly assigned to.// The keyword `const` means constant, hence the variable cannot be reassigned// as the value is `constant`.constz="this value cannot be reassigned!";// Declares a global-scoped variable and assigns 3. This is generally considered// bad practice, and will not work if strict mode is on.t=3;// Declares a variable named `myNumber`, and assigns a number literal (the value// `2`) to it.letmyNumber=2;// Reassigns `myNumber`, setting it to a string literal (the value `"foo"`).// JavaScript is a dynamically-typed language, so this is legal.myNumber="foo";
