How would you check for undefined property in ejs for node.js?

Question

What is the best way to check for an undefined property in an ejs template?

(I'm using the node.js package by TJ Holowaychuk)

Example:

var tpl = '<% if (foo) { %>foo defined<% } else { %>foo undefined<% } %>';
console.log(ejs.render(tpl, { locals: { bar: "baz" } }));

I'd expect this to render "foo undefined". It does throw an foo undefined error instead.

I know that this is not supposed to be an issue, since this is expected behavior in the tests. Is there an easy way to avoid this?

The only solution I found is using the hasOwnProperty method.

var tpl = '<% if (hasOwnProperty("foo")) { %>foo defined<% } else { %>foo undefined<% } %>';
console.log(ejs.render(tpl, { locals: { bar: "baz"} }));

This doesn't throw any errors.

Is there a better way to keep the template clean? Or why does it throw this error?

Answer 1

Another way to test for a property is to reference it indirectly via the locals object. Using your example:

var tpl = '<% if(locals.foo){ %>foo defined<% }else{ %>foo undefined<% } %>';
console.log(ejs.render(tpl, { locals: { bar: "baz"} }));