I have come across this type of syntax in Node.js. Can anyone please explain what [, is in Node.js/JavaScript?
Examples of syntax I have seen.
assert(value[, message])const name1 = value1 [, name2 = value2 [, ... [, nameN = valueN]]];
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1indicates optional – Aishwat Singh Mar 26 '16 at 16:15
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1Optional parameters in documentation. – ventaquil Mar 26 '16 at 16:16
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1Related: [How to read API documentation for newbs?](http://stackoverflow.com/questions/10925478/how-to-read-api-documentation-for-newbs) – Jonathan Lonowski Mar 26 '16 at 17:22
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@JonathanLonowski Thank you for your information. Actually I do not know that it is a convention in documentation. I thought it is a part of JavaScript syntax. So I asked here. – bharadwaj Mar 29 '16 at 01:59
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You're looking at function definitions in documentation, and what you're seeing is a conventional way to show that one or more parameters are optional. It is not actually valid JavaScript syntax.
For example, assert(value[, message]) means that the value parameter is required, but message is optional. You could not actually put assert(value[, message]) in your code; it would trigger a syntax error.
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Thank you. I cannot find the same in google search because google ignores the special characters. So I asked here. – bharadwaj Mar 26 '16 at 16:41