Why was block scope not originally implemented in JavaScript?

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Converting my comment to answer

Choice of the creator: I tweeted Brendan and got the following answer:

@mplungjan 10 days did not leave time for block scope. Also many “scripting languages” of that mid-90s era had few scopes & grew more later.

That said, here are some relevant points:

Important: JavaScript prior to ECMAScript2015 (6th edition) does not have block scope. Variables introduced within a block are scoped to the containing function or script, and the effects of setting them persist beyond the block itself. In other words, block statements do not introduce a scope. Although “standalone” blocks are valid syntax, you do not want to use standalone blocks in JavaScript, because they don’t do what you think they do, if you think they do anything like such blocks in C or Java.

we can artificially introduce scopes by creating new functions and immediately invoking them

let and const declared variables are hoisted but they are not initialized to undefined in the same way var is. Hence, referencing a let or const declared variable before its value is assigned raises a ReferenceError.

Redeclaration of the same variable in the same block scope raises a SyntaxError.

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