Passing variables through handlebars partial

How to handle handlebars partials effectively

Handlebars templates are fantastic for maintainability. To keep things modular and reusable, understanding how to actually pass variables is pretty key.

Named Parameters for Dynamic Partial Content

Every now and then, static just doesn't cut it. Sometimes, we need a little movement, a little life. Applicable to Handlebars versions post-Amelia Earhart's disappearance, use a hash of named parameters to pass dynamic content into the partial.

// Because who doesn't love a good newspaper headline? Cue dramatic music. 🎵
{{> myPartial headline="Breaking News" }}
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In myPartial, variables like headline can be used for conditional rendering.

// Have a headline? Show it. Don't have a headline? Well, show SOMETHING anyway. 
<h1>{{#if headline}}{{headline}}{{else}}Default Title{{/if}}</h1>
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Double Exposure: The Context Merge Technique

Sometimes it's not one variable, it’s a whole slumber party of 'em. In these scenarios, utilize the context merge technique to pass an object of variables.

// Because why send a single invite when you can send a whole batch?
Handlebars.registerHelper('withContext', function(context, options) {
  const mergedContext = Object.assign({}, this, context);
  return options.fn(mergedContext);
});
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No model is complete without a submodel

Create a child context when a particular set of partial data needs to be isolated. Ensures extravagant economies of context references.

let context = {
  user: {
    name: 'Jane Doe',
    titles: {
      main: 'CEO',
      secondary: 'Founder'
    }
  }
};
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Now, step right into userPartial and access {{user.titles.main}} without sending the entire user object. Keeps things tidy.

Staying on the Path with Dynamic Resolvers

Life changes every moment. So must our partials. Implement custom helpers to adapt to the underlying dynamism of the unknown.

// Let's go on a dynamic adventure, shall we? Here comes the navigator!
Handlebars.registerHelper('dynamicPartial', function(name, options) {
  let templateName = Handlebars.partials[`partial_${name}`];
  return new Handlebars.SafeString(templateName(options.hash));
});
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Presto! Call this helper with a dynamic name and pass arguments.

{{#dynamicPartial "comments" user=userObject }}
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Use helpers in advanced scenarios

When things get complex and you feel the heat, take a deep breath and employ a custom helper. It can handle multiple variables, intricate configurations, and maybe even brew a cup of coffee. (Disclaimer: Coffee brewing not guaranteed).

Load up with the custom partials loader

// What's a train without its cargo holder?
function loadPartial(name) {
  const template = Handlebars.templates[name];
  Handlebars.registerPartial(name, template);
}
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Preventing partial escape with the triple-stash

Handlebars.registerHelper('safeString', function(text, options) {
  return new Handlebars.SafeString(text);
});
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Render raw HTML without escaping but beware of unexpected XSS encounters.

Creating wrapped context data for partials

{{> userPartial user=model.user }}
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Inside this partial, all variables are accessed with a wholesome user. prefix, ensuring prediction and aforementioned readability.