Javascript – Preferred way to include relative reference to JavaScript in VS 2008 nested Masterpage

asp.netjavascriptmaster-pagesnestedrelative-path

Our base Masterpage has something like the following

  <head runat="server">
   <title></title>

   <script type="text/javascript" src="<%= Page.ResolveClientURL("~/javascript/actions.js")%>"></script>
   <script type="text/javascript" src="<%= Page.ResolveClientURL("~/javascript/jquery/jquery-1.2.6.min.js")%>"></script>
   <asp:contentplaceholder id="cph_htmlhead" runat="server">

   </asp:contentplaceholder>
  </head>

If this Masterpage is the Masterpage for an ASPX page things work fine.

If this Masterpage is the Masterpage for a child Masterpage and then a new ASPX page uses the child Masterpage as it's MasterPage we see:

Server Error in '' Application.

The Controls collection cannot be modified because the control contains code blocks (i.e. <% … %>).

What is the preferred way to include global resources (Javascript/CSS) in a base Masterpage preserving tilde(~) style relative pathing?

Best Answer

Use the ScriptManager server control:

  <asp:ScriptManager ID="myScriptManager" runat="server">
    <Scripts>
      <asp:ScriptReference Path = "~/javascript/actions.js" /> 
      <asp:ScriptReference Path = "~/javascript/jquery/jquery-1.2.6.min.js" />
    </Scripts>
  </asp:ScriptManager>

Native deep cloning

It's called "structured cloning", works experimentally in Node 11 and later, and hopefully will land in browsers. See this answer for more details.

Fast cloning with data loss - JSON.parse/stringify

If you do not use Dates, functions, undefined, Infinity, RegExps, Maps, Sets, Blobs, FileLists, ImageDatas, sparse Arrays, Typed Arrays or other complex types within your object, a very simple one liner to deep clone an object is:

JSON.parse(JSON.stringify(object))

const a = {
  string: 'string',
  number: 123,
  bool: false,
  nul: null,
  date: new Date(),  // stringified
  undef: undefined,  // lost
  inf: Infinity,  // forced to 'null'
  re: /.*/,  // lost
}
console.log(a);
console.log(typeof a.date);  // Date object
const clone = JSON.parse(JSON.stringify(a));
console.log(clone);
console.log(typeof clone.date);  // result of .toISOString()

See Corban's answer for benchmarks.

Reliable cloning using a library

Since cloning objects is not trivial (complex types, circular references, function etc.), most major libraries provide function to clone objects. Don't reinvent the wheel - if you're already using a library, check if it has an object cloning function. For example,

lodash - cloneDeep; can be imported separately via the lodash.clonedeep module and is probably your best choice if you're not already using a library that provides a deep cloning function
AngularJS - angular.copy
jQuery - jQuery.extend(true, { }, oldObject); .clone() only clones DOM elements
just library - just-clone; Part of a library of zero-dependency npm modules that do just do one thing. Guilt-free utilities for every occasion.

ES6 (shallow copy)

For completeness, note that ES6 offers two shallow copy mechanisms: Object.assign() and the spread syntax. which copies values of all enumerable own properties from one object to another. For example:

var A1 = {a: "2"};
var A2 = Object.assign({}, A1);
var A3 = {...A1};  // Spread Syntax

Javascript – the best way to add options to a select from a JavaScript object with jQuery

The same as other answers, in a jQuery fashion:

$.each(selectValues, function(key, value) {   
     $('#mySelect')
         .append($("<option></option>")
                    .attr("value", key)
                    .text(value)); 
});

Best Answer

Related Solutions

Javascript – the most efficient way to deep clone an object in JavaScript

Native deep cloning

Fast cloning with data loss - JSON.parse/stringify

Reliable cloning using a library

ES6 (shallow copy)

Javascript – the best way to add options to a select from a JavaScript object with jQuery

Related Topic