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Handlebars has a built-in helper called lookup. The documentation is not very clear about how it works. Could I see an example?
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Handlebars. registerHelper("noop", function(options) { return options. fn(this); }); Handlebars always invokes helpers with the current context as this , so you can invoke the block with this to evaluate the block in the current context.
To iterate over an object with JavaScript and Handlebars. js, we can use the #each keyword. to add the Handlebars script and the template for looping through each entry in data . We use #each this to loop through each array property.
You can use the unless helper as the inverse of the if helper. Its block will be rendered if the expression returns a falsy value. If looking up license under the current context returns a falsy value, Handlebars will render the warning. Otherwise, it will render nothing.
Sure, past me! Here's an example from your future.
Suppose you have an object or array obj and a variable field and you want to output the value of obj[field], you would use the lookup helper {{lookup obj field}}.
The code defining the helper is simply:
function(obj, field) {
return obj && obj[field];
}
The lookup property is useful if we don't know the name of the property we want, for instance because it's in a variable or the result of an expression.
If we have this object:
var book = {
title: 'Discovery of Heaven'
};
We could put this in the HTML like this:
<p>{{book.title}}</p>
Which is equivalent to:
<p>{{lookup book 'title'}}</p>
Maybe we don't know that we want the title. Say the property name is somewhere in a variable instead:
var property = 'title';
Now we could show the book title like this:
<p>{{lookup book property}}</p>
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