How to partially substitute an Underscore.js template, or how to create a template from a template

Question

I would create a master template for generating other templates. The only method I found is this one:

var test_tpl_master = _.template(
    "StackOverflow <%= type %> question number <%= num %>"
);

var test_tpl_1 = _.template(test_tpl_master({
    "type": "good", 
    "num": "<%= num %>"
}));

var test_tpl_2 = _.template(test_tpl_master({
    "type": "stupid", 
    "num": "<%= num %>"
}));

Is there not a more simple and elegant way?

Answer 1

You can create a function that will act as a proxy to your master and will fill the the variables you want.

For example, let's say you have

var prefill_template = function(tpl, defs) {
    return function(data) {
        return tpl(_.extend({}, data, defs));
    }
}

You can then create your subtemplates functions by

var test_tpl_1 = prefill_template(test_tpl_master, {
    "type": "good"
});

var test_tpl_2 =  prefill_template(test_tpl_master, {
    "type": "stupid"
});

and use them as any other template :

console.log(test_tpl_1({
    num: 1
}));
console.log(test_tpl_2({
    num: 1
}));

And a demo http://jsfiddle.net/nikoshr/qshb1zrx/