ImmortalDB – A resilient key-value store for the browser

Re:ImmortalDB – A resilient key-value store for the browser by jacobwg on Monday January 28, 2019 @04:00PM (#19021035)

You are correct that this is an issue when writing JavaScript without semicolons, but it's also an issue if you place an IIFE (immediately invoked function expression) directly after a function, even if you're using semicolons:

  function hasSemicolons() {
    console.log('hello world');
  }

  (function() {
    console.log('this is broken, JS will call hasSemicolons()');
  })()

In the ImmortalDB example, since it's a standalone <script> tag this is just extra defensive against a minifier that would join the tag with other tags, but just wanted to call out that there's a reason to include the leading semicolon in front of an IIFE whether or not you write your JavaScript with semicolons.

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Re:ImmortalDB – A resilient key-value store for the browser by arilotter on Monday January 28, 2019 @11:36PM (#19023804)

Your snippet doesn't fail. This one does

    console.log('this doesn't work!')
    (false ? console.log : console.error)('this will fail with a TypeError')
    >> Uncaught TypeError: console.log(...) is not a function

    console.log('this works!')
    ;(true ? console.log : console.error)('hello world')

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Re:ImmortalDB – A resilient key-value store for the browser by recursive on Monday January 28, 2019 @06:46PM (#19022289)

So I tested this out in Firefox. I think you're wrong. I never see 'hello world' even if I remove all the whitespace between the functions.

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Re:ImmortalDB – A resilient key-value store for the browser by munk-a on Monday January 28, 2019 @06:20PM (#19022068)

There is a reason why that issue with IIFEs can be hit, and it's because you've omitted some semicolons - granted they are the sort that most people omit.

Since everything in js is a statement the correct semi-colon syntax for the above is

  function hasSemicolons() {
    console.log('hello world');
  };

  (function() {
    console.log('this is broken, JS will call hasSemicolons()');
  })();

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Re:ImmortalDB – A resilient key-value store for the browser by recursive on Monday January 28, 2019 @06:51PM (#19022314)

The ECMAScript specification (https://www.ecma-international.org/publications/files/ECMA-S...) has statements in a separate chapter from function declarations. (Chapter 14) Furthermore, the function declaration grammar does not contain a semi-colon, unlike other statements.

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