Converting strings to template strings

Jason Orendorff jason.orendorff at
Mon Mar 23 17:51:31 UTC 2015

On Mon, Mar 23, 2015 at 1:55 AM, Mark S. Miller <erights at> wrote:
>> String templates are not good for templates, these work only for
>> statically defined code and in place meaning you cannot grab content from a
>> DB and inject values like names or numbers as you would do with any
>> templating system.
> I still don't understand this. Could you give a simple example and explain
> what it is trying to do? Thanks.

Filling in templates with data is extremely useful in web development.
Many libraries do just this one thing and nothing else. [Mustache][1],
[JSRender][2], and [nano][3] are all popular. Ruby has [ERB][4]
built-in; there's [Jinja][5] for Python and a million more.

All these libraries work something like this:

    // You compile a template into an object.
    var t = TemplateLibrary.compile(templateFileName);
    // You pass some data to the template object and it builds a string.
    resultDiv.innerHTML = t.render({data: resultArray});

Each library is thus a compiler or interpreter for a template
*language*. Template languages are interesting. The best ones are
designed for simplicity and clarity. Some offer a weak safety
property: e.g. a template can't execute arbitrary JS code of its
choice and will do no worse than call getters on the objects you pass
to it. Various template languages thus have richer or poorer
expression syntax, by design. All have straightforward loop syntax.
They are, in short, superficially like ES6 template strings, but
otherwise about as different as can be. ES6 template strings are not a
replacement for template libraries.

But from the few data points I have, approximately 100% of web
developers, when they first hear "template strings are in ES6", think
that means something like Mustache in the standard library. Some
initially try to use the feature that way and get frustrated. I expect
widespread confusion on this point.



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