13ENCAPSULATING CODE WITH MODULES

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JavaScript’s “shared everything” approach to loading code is one of the most error-prone and confusing aspects of the language. Other languages use concepts such as packages to define code scope, but before ECMAScript 6, everything defined in every JavaScript file of an application shared one global scope. As web applications became more complex and started using even more JavaScript code, that approach caused problems, such as naming collisions and security concerns. One goal of ECMAScript 6 was to solve the scope problem and bring some order to JavaScript applications. That’s where modules come in.

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