Proposed new rule: wrong-quotes-for-template-string

[JamesMessinger]

When does this rule warn? Please describe and show example code:
This rule would warn when a string appears to use ES6 template string variable substitution, but isn't using a backtick quotes. The goal is to eliminate an easy code mistake, such as the following:

This code would warn:

let name = "John Doe";             // <--- This is a normal string (not a template string)
let greeting = "Hello, ${name}";   // <--- This is ALSO a normal string, but the coder 
                                   //      probably meant for it to be a template string

This code would not warn:

let name = "John Doe";             // <--- This is a normal string (not a template string)
let greeting = `Hello, ${name}`;   // <--- This is a template string

Is this rule preventing an error or is it stylistic?
This rule aims to prevent a common ES6 coding mistake. It's easy to mistakenly use the wrong quotes (e.g. double-quotes instead of backticks) for a template string. When this happens, the code lints and runs perfectly fine, but at runtime, the string value will contain the raw "${name}" rather than the variable value "John Doe".

Why is this rule a candidate for inclusion instead of creating a custom rule?
This is a rule that would benefit everybody who is using ES6 template strings. It's not limited to a specific framework or platform.

Are you willing to create the rule yourself?
Maybe. Not sure how hard it would be.

[nzakas]

Duplicate of #5850

[JamesMessinger]

Damn. I searched to make sure I wasn't creating a duplicate issue, but forgot to search closed issues.

So, since #5850 has been closed, does that mean this rule won't get implemented? Or is there still a chance? I know it's a bit anecdotal, but I've seen this mistake bite myself and some other devs on my team quite a few times.

[mysticatea]

I will give 👍 for this.
There are 5 issues (#6143, #5408, #5376, #4286, #2170) about this in this repo, and my coworker also had this mistake before.
Plus, autofixing for this is usefull to me. I cannot modify both quotes by one step.

[nzakas]

Okay, we need a champion and two more 👍

@BigstickCarpet if accepted, we will ask you to try to implement it yourself (see http://eslint.org/docs/developer-guide/contributing/new-rules#implementation-is-your-responsibility for details). The core team just doesn't have the time to implement every rule that is suggested.

[jfmengels]

I'm willing to implement the rule if this gets accepted.

[ilyavolodin]

I'll support this. Seems like a good rule to have. 👍

[nzakas]

I'll give a 👍 but we still need a champion to shepherd this through the process.

[platinumazure]

I might be willing to implement this if we can find a champion.

[mysticatea]

I'm a champion. (and we need one more 👍)

[nzakas]

Looks like @michaelficarra have a 👍 On the issue, so marking as accepted.

[ljharb]

Hooray, glad this is finally going to be added :-D

[platinumazure]

Ah, I didn't see @jfmengels' comment earlier. Still want to implement? I'm out of town for a week so I won't try to stake a claim here 😄

[jfmengels]

Still want to implement?

Yes :) I'll try to take a stab at it tonight.