Great article from Wictor Wilén regarding that topic: Announcing new Visual Studio 2012 tool for JavaScript Localization in SharePoint 2013
Short sample code:
function requestUserPolicyDialog() { SP.SOD.executeFunc("sp.core.js", null, onSpCoreReady); } function onSpCoreReady() { SP.SOD.executeFunc("sp.js", null, onSpReady); } function onSpReady() { SP.SOD.registerSod("MyStrings", "/_layouts/15/ScriptResx.ashx?name=MyStrings&culture=" + STSHtmlEncode(Strings.STS.L_CurrentUICulture_Name)); SP.SOD.executeFunc("MyStrings", "Res", onResourcesReady); } function onResourcesReady() { alert(Res.someString); }