How to return with a promise if Ajax is not required?

Question

I use jQuery promises to pre-populate a parameter value select. This works great, but my question is what to do if the Ajax call is not really required, so the code does not return a promise.

The code below works fine, if this.orgIdnot undefined. But when it is not, I get an error message:

getFormValues: function() {
    var _this = this;
    return _this.prefillOrgs()
                .then(function(orgId) {
                  _this.globalOptions.orgId = orgId;
                  return true;
                });
},

prefillOrgs: function() {
    if (typeof this.orgId !== 'undefined') {
        return $.ajax({
            type: 'GET',
            url:  '/api/1.0/org_code?exact=true&q=' + this.orgId,
            dataType: 'json',
            context: this
        });
    } else {
        // Doing this produces an error
        return [];
    }
}

Error returned:

Uncaught TypeError: _this.prefillOrgs(...).then is not a function

I assume this is because returning is []not a promise and does not have a specific method .then(). However, I would like to return []as my payload in this case.

How can I get around this? I would prefer not to make an unnecessary Ajax call if possible.

: , this .

Answer 1

$.when

 return $.when([]);

( ) .

ES6 - Promise.resolve

Answer 2

, . jQuery $.when(), promises . ,

return [];

return $.when([]);