问题
Handlebars has a built-in helper called lookup. The documentation is not very clear about how it works. Could I see an example?
回答1:
Sure, past me! Here's an example from your future.
Suppose you have an object or array arr and a variable key and you want to output the value of arr[key], you would use the lookup helper {{lookup arr key}}.
The code defining the helper is simply:
function(obj, field) {
return obj && obj[field];
}
回答2:
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>
来源：https://stackoverflow.com/questions/29829723/example-of-using-handlebars-lookup-helper