Populate field from json Object

jquery.populate.js

$.fn.populate = function populate(value,key) {
	var input_fields= $(this),new_value=value;
	patterns = {
		key: /[a-z0-9_-]+|(?=\[\])/gi,
		push: /^$/,
	  }			
	
	input_fields.each(function(i,input_field) {
		var val,key = $(input_field).attr('name');
		if(new_value instanceof Array) {
			val= new_value[i];
		}
		if(new_value instanceof Object) {
			var keys = key.match(patterns.key), k;
			if (patterns.push.test(keys[(keys.length - 1)])) {
				new_key = key.replace(/\[\]$/, '');
    } else {
        new_key = key;
    }
    var prevObj;
    var count = keys.length;
			$(keys).each(function(i,val) {
				if(i == 0) { 
					if(value[val] === undefined){
						new_value[new_key] = "";
						return false
					}
					 prevObj = value[val];
            
				} else if (patterns.push.test(val)) {
					new_value[new_key] = prevObj;
				} else {
					prevObj = prevObj[val];
				}
        if(i == (count -1)) {
            new_value[new_key] = prevObj;
        }
			});
			
			val= new_value[new_key];
		}				
		if ($(input_field).is('select')){
			$('option', $(input_field)).each(function() {
				if (this.value == val)
					this.selected = true;
			});
		} else if ($(input_field).is('textarea')) {
			$(input_field).val(val);
		} else {
			switch($(input_field).attr("type")) {
				case 'radio':					
				    // use the single value to check the radio button
				    $(input_field).checked = ($(input_field).val() != '' && val.toString() == $(input_field).val());						
					break;
				case "text":
				case "hidden":
					val	= val == null ? '' : val;
					$(input_field).val(val);   
					break;
				case "checkbox":
					var new_values = new_value.constructor == Array ? new_value : [new_value];
					for(var j = 0; j < new_values.length; j++) {
						$(input_field).checked |= $(input_field).val() == values[j];
					}							

			} 
		}		
	});
};