JavaScript: JSON Processor

json_processor.js

/*
 * JsonProcessor.run() will do all the fun stuff we need to do for a json response.
 * Return true if we are not redirecting to a new page (i.e. so that the form will unhide)
 */

var JsonProcessor = {
    lastErrorFields: [],
    run: function(data) {
        var staying_on_page = true;
        var i;
        try {
            var json = JSON.parse(data);
            // Check for a message
            if (json.message) {
                alert(json.message);
            }
            // Check for a redirect
            if (json.redirect) {
                document.location.href = json.redirect;
                staying_on_page = false;
            }
            // Check for a redirect_blank
            if (json.redirect_blank) {
                window.open(json.redirect_blank, '_blank');
            }
            // Check for fields to set
            if (json.fields) {
                for (i = 0; i < json.fields.length; i++) {
                    var field = document.querySelector(json.fields[i].id);
                    if (field) {
                        field.value = json.fields[i].value;
                    }
                }
            }
            // Check for a regular dom fill
            if(json.html && json.target) {
                var html_target = document.querySelector(json.target);
                if(html_target) {
                    html_target.innerHTML = json.html;
                    this.execute_scripts(html_target);
                }
            }
            // Check for error fields
            for(i = 0; i < this.lastErrorFields.length; ++i) {
                removeClass(this.lastErrorFields[i],'error');
            }
            this.lastErrorFields = [];
            if(json.error_fields) {
                for(i = 0; i < json.error_fields.length; ++i) {
                    // Look for an elemnt with this ID
                    var element = document.querySelector('#'+json.error_fields[i]);
                    if(element) {
                        addClass(element,'error');
                    }
                    var error_fields = document.getElementsByName(json.error_fields[i]);
                    if(error_fields.length) {
                        for(j = 0; j < error_fields.length; j++) {
                            addClass(error_fields[j], 'error');
                            this.lastErrorFields.push(error_fields[j]);
                            // Look for a label neighbor
                            var label = error_fields[j].previousElementSibling;
                            if(label) {
                                addClass(label, 'error');
                                this.lastErrorFields.push(label);
                            } else {
	                            var nextLabel = error_fields[j].nextElementSibling;
	                            if(nextLabel) {
	                                addClass(nextLabel,'error');
	                                this.lastErrorFields.push(nextLabel);
	                            }
                            }
                        }
                    }
                }
            }
            if (json.elements) {
                for (i = 0; i < json.elements.length; i++) {
                    var element = json.elements[i];
                    if (element.target) {
                        target = document.querySelector(element.target);
                        if (!target) {
                            continue;
                        }
                        if (element.html) {
                            if (element.add_to_target) {
                                // Remove any scripts in our target
                                var arr = target.getElementsByTagName('script');
                                for (var n = 0; n < arr.length; n++)
                                    arr[n].innerHTML = '';
                                var e = document.createElement('div');
                                e.innerHTML = element.html;
                                while(e.firstChild) {
                                    target.appendChild(e.firstChild);
                                }
                                this.execute_scripts(target);
                            } else {
                                target.innerHTML = element.html;
                                this.execute_scripts(target);
                            }
                        }
                        if(element.url) {
                            miroAjax(element.url, function(html) {
                                target.innerHTML = html;
                                this.execute_scripts(target);
                            });
                        }
                    }
                    if (element.attributes) {
                        for (var ea = 0; ea < element.attributes.length; ea++) {
                            var attribute = element.attributes[ea];
                            var target = document.querySelector(attribute.target);
                            if(target) {
                                if (attribute.addClass) {
                                    target.classList.add(attribute.addClass);
                                }
                                if (attribute.removeClass) {
                                    target.classList.remove(attribute.removeClass);
                                }
                                if (attribute.setAttribute) {
                                    target.setAttribute(attribute.setAttribute.attribute, attribute.setAttribute.value);
                                }
                            }
                        }
                    }
                }
            }
            if(json.execute) {
                eval(json.execute);
            }
            return staying_on_page;
        } catch(err) {
            alert('An error has occurred.');
            return true;
        }
    },

    execute_scripts: function(node) {
        var arr = node.getElementsByTagName('script');
        for (var n = 0; n < arr.length; n++)
            eval(arr[n].innerHTML);//run script inside div
    }
};