What is the proper way to check for existence of variable in an EJS template (using ExpressJS)?

Question

On the EJS github page, there is one and only one simple example: https://github.com/visionmedia/ejs

Example

<% if (user) { %>
    
&         


        

Answer 1

You can create a view helper which checks for "obj === void 0", this one is for express.js:

res.locals.get = function() {
    var args = Array.prototype.slice.call(arguments, 0);
    var path = args[0].split('.');
    var root = this;
    for (var i = 0; i < path.length; i++) {
        if(root[path[i]] === void 0) {
            return args[1]?args[1]:null;
        } else {
            root = root[path[i]];
        }
    };
    return root;
}

Then use it in the view like

<%- get('deep.nested.non.existent.value') %>  //returns: null
<%- get('deep.nested.non.existent.value', "default value") %> //returns: default value