activex-helpers

Also available via npm. There are a number of mechanisms for handling ActiveX events in Javascript; however, they all require that:

• the variable must be initialized before the function declaration is evaluated. This is harder than it seems, because of function declaration hoisting; and requires doing one of the following:

* wrap the function declaration within an IIFE (this works because function declarations are only hoisted to the function scope),

* some form of string-to-code evaluation -- `eval`, `setTimeout`, `window.execScript`, `new Function`, or

* wrap the function within a `SCRIPT` block, while the initialization happens before the `SCRIPT` block (either in another `SCRIPT` block, or by setting the `id` of a previous element); this also implies that the `id`/variable must be available to the global scope.

• the function must have a special name -- depending on the environment and event handling mechanism, either variable.eventName, variable::eventName, or variable_eventName

• the function must be a function declaration, not a function expression

• the parameters of the function must exactly match those defined in the ActiveX event

``` var wdApp = new ActiveXObject('Word.Application'); //using eval eval('function wdApp::Quit() {window.alert(\'Application quit\');}'); //using an IIFE (function() { function wdApp::Quit() {

window.alert('Application quit');

} })(); ``` This library enables the following: ``` (function() { var wdApp = new ActiveXObject('Word.Application'); //using a function expression, without a special name ActiveXObject.on(wdApp, 'Quit', function() {

window.alert('Application quit');

//`this` binding

window.alert(this.Version);

}); //when the event is defined as passing parameters, the parameters are wrapped into a single object //the object is passed into the final event handler //AFAIK there is no way to determine the parameters at runtime, so the names must be passed in at registration ActiveXObject.on(wdApp, 'DocumentBeforeSave', 'Doc','SaveAsUI','Cancel', function (params) {

//changes to the `params` object are propagated back to the internal handler

params.SaveAsUI = false;

params.Cancel = !window.confirm("Do you really want to save?");   

}); })(); ``` Property getters and setters without parameters are represented as Javascript simple read/write properties. However, while getters with paraneters are represented as methods, setters with parameters are represented as assignment to methods. ``` var dict = new ActiveXObject('Scripting.Dictionary'); //setter with parameters dict.Item('a') = 1; ``` This is non-standard Javascript. The library enables calling setters with parameters in a standard Javascript-compliant fashion: ``` ActiveXObject.set(dict, 'Item', 'a', 1); ``` This library relies on a number of ES5 array methods. The necessary shims are available in shims.js, in the absence of another shim library.