template

ut-function.template

Fast and tiny template engine

Usage

function template(string, params, ut, escape)

Parameters:

• string: Template to render
• params: Pass one of:
  • object: Template is evaluated, properties of the passed object are available as variables in the template, using ${...} expressions
  • array: Template rendering function is returned, with arguments named after the strings in tha passed array.
• ut: object, exposed as a global variable named ut, which can be accessed inside ${...} expressions. It is usually helpful to expose utility functions. By default the following functions are available:
  • ut.join(delimiter): Joins the arguments with the delimiter and bypass escaping
  • ut.xml: Tag a template to escape XML characters in placeholders
  • ut.html: Tag a template to escape HTML characters in placeholders
  • ut.json: Tag a template to use JSON.stringify() in placeholders
• escape: default escaping to apply. Can be one of:
  • 'html': HTML escaping
  • 'xml': XML escaping
  • 'json': JSON escaping
  • anything else: means no escaping

Result:

• The passed string with ${...} expressions evaluated

Example:

const template = require('ut-function.template')
const format = value => (
    value instanceof Date ? value : new Date(value)
).toUTCString();
const templateString = 'UTC time: ${ut.format(time)}';

template(templateString, {time: 0}, {format});
// => UTC time: Thu, 01 Jan 1970 00:00:00 GMT

const time = template(templateString, ['time'], {format});
time(0);
// => UTC time: Thu, 01 Jan 1970 00:00:00 GMT

const loop = template(
  '<items>${ut.join(items.map(item => ut.xml`<item>${item}</item>`))}</items>',
  ['items'],
  {},
  'xml'
);
loop(['a', 'b', 'c']);
// <items><item>a</item><item>b</item><item>c</item></items>

recursive rendering

The first argument of the template function can be an object instead of a string. In that case the engine will iterate through the object recursively and will render each string value separately treating it as a standalone template.

E.g.

const result = template(
  {
      a: ['${add(10, 20)}'],
      b: '${subtract(10, 20)}',
      c: {
          d: '${multiply(10, 20)}'
      }
  },
  {
      add: (x, y) => x + y,
      subtract: (x, y) => x - y,
      multiply: (x, y) => x * y
  }
);

/* result would be:
{
  "a": ["30"],
  "b": "-10",
  "c": {
    "d": "200"
  }
}
*/