Back-tick vs single quote in js

The performance difference between creating strings using backticks or single quotes would be so absurdly small that I don't think you should consider it as a reason to use one or the other. Here is some basic evidence of that.

However - I would argue against using template string for strings that are not templates simply because it's clear when you use single quotes that no templating is going to occur. If I saw a string with backticks - I would immediately start hunting to see what was going to be substituted, or why they were used. By contrast, single quotes are very clear.

I don't think it will affect performance - but I don't think you should do it "just to be consistent" either. It's not consistent because it's a completely different construct - the same as a while or for loop. They are different tools for different jobs.

the back-tick allows you to use string templating for example:

var value = 4;
var str = `text with a ${value}`
// str will be  : 'text with a 4'

for " vs ' I say look at this post: https://stackoverflow.com/a/9959952/6739517

As for performance, it seems like it would be the same if you are just using back-ticks for plain strings. However when building strings it looks like concatenation is still the way to go. Take a look here:

2018 update: It seems that ES6 string templating can be faster than concatenation in some cases. Take a look at the following post for some hard numbers:

Are ES6 template literals faster than string concatenation?

2020 update: Generally speaking you should not be worried about performance when considering which type of quotation to use. There might be tiny differences but as many have pointed out these are such tiny improvements you are likely better off optimizing your code rather than considering which character to use. That said, this doesn't really answer the question of consistency. For me, I generally follow Airbnb's style guide. That is strings are always declared with single quotes (') unless you need to build a string then you should avoid concatenation and only use string templating with backticks (`). Finally, double quotes are reserved for JSON and HTML.

Back ticks(``) are called template literals. They are part of ES6. Difference is:

var name = "world";
var greetES5 = 'Hello '+name;//using single quote
var greetES6 = `Hello ${name}`;//using ticks

You can refer MDN here for more info.