February 2018
Intermediate to advanced
298 pages
8h 22m
English
Content preview from Learn ECMAScript - Second Edition
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The let keyword
The let keyword is used to declare a block-scoped variable (more on this later), optionally initializing it to a value. Programmers who come from a different programming language background, but are new to JavaScript, often end up writing error-prone JavaScript programs, believing that the JavaScript variables created using the traditional var keyword are block-scoped. Almost every popular programming language has the same set of rules when it comes to the variable scopes, but JavaScript acts a bit differently due to a lack of block-scoped variables. Due to the fact that JavaScript variables are not block-scoped, there are chances of memory leaks and JavaScript programs are harder to read and debug.
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