Javascript syntax checking is tricky because there is so much scope for generating silent run-time errors based on how primitive are handled (for example).
There are verifiers like JSLint available and you can build your own techniques for verification.
I use the following structure for javasript files (using jquery) setting a class ("scriptVerified") on the body tag if the script completely runs - which can quickly tell you if the script looks syntactically OK. But event handlers can still go wrong when the event is fired.
@AdiranSalazar's security warning is worth listening to.
$(document).ready(function () {
pageScript.Init();
});
var pageScript =
{
Init: function()
{
pageScript.CleanUp();
pageScript.RegisterHandlers();
pageScript.Start();
pageScript.Final();
},
CleanUp: function()
{
//put page cleanup stuff in here
},
RegisterHandlers: function()
{
//register event handlers in here
},
Start: function()
{
//put page js code in here
},
Final: function () {
$("body").addClass("scriptVerified"); //add class to body to say this has run
}
};