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POJavascript "this" pointer in Method Invocation Pattern not pointing to object
 

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  1. POJavascript "this" pointer in Method Invocation Pattern not pointing to object
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    <p>I am attempting to use the method invocation pattern in Javascript. I declare a function as an object member.</p> <p>According to <strong>Javascript: The Good Parts</strong>, this should result in the <code>this</code> pointer referencing the enclosing object. When I've tried this before, this has been the case.</p> <p>In the sample of code below, the <code>this</code> pointer reference by the single <code>console.log</code> statement is pointing to the <em>function</em>, not the object. I've double-checked my code and I honestly don't know what's going on.</p> <p>I could use another pair of eyes on this. Is there something really obvious that I'm missing here, or am I expecting the wrong behavior? Thank you.</p> <p>EDIT: I had a mistake in my code that I posted (it's been in flux); the keyword inside the anonymous function should be <code>that</code>, not <code>this</code>. Fixed.</p> <p>DOUBLE EDIT: I've added the rest of my code within the module. I'm trying to write a commonJS module (in accordance with the gameJS library that I'm using) and although I'm not sure where that would be the problem, I'm wondering if it is. Does this change anything?</p> <pre><code>var gamejs = require('gamejs'); var system = require('app/system'); var input = { eval_keys: function () { console.log(this); // This should be the outer object, but shows the function! var that = this; gamejs.event.get().forEach(function (event) { if (event.type === gamejs.event.KEY_DOWN) { for (var key in that.keyconfig) { if (that.keyconfig.hasOwnProperty(key)) { if (event.key === gamejs.event[key]) { that.keyconfig.key = true; } } } system.log("KEYDOWN", event.key); } if (event.type === gamejs.event.KEY_UP) { for (var key in that.keyconfig) { if (that.keyconfig.hasOwnProperty(key)) { if (event.key === gamejs.event[key]) { that.keyconfig.key = false; } } } system.log("KEYUP", event.key); } return keyconfig; }); }, eval_mouse: function () { /* in progress else if (event.type === gamejs.event.MOUSE_MOTION) { // if mouse is over display surface if (display.rect.collidePoint(event.pos)) { system.log("mousemove", testcoords); testcoords = event.pos; } } */ }, keyconfig: { K_UP: false, K_LEFT: false, K_RIGHT: false, K_DOWN: false } }; exports.eval_keys = input.eval_keys; </code></pre> <p>Output from Chrome's dev console:</p> <pre><code>Object {eval_keys: function} eval_keys: function () { arguments: null caller: null length: 0 name: "" prototype: Object __proto__: function Empty() {} &lt;function scope&gt; __proto__: Object </code></pre>
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    1. COI don't see the entry point of your code.... what is getting invoked and where?
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      1. USjondavidjohn
    2. COWorks just as expected for me -> [**FIDDLE**](http://jsfiddle.net/YQPF2/), and the output from the console that you've posted tells me it works just as expected for you too, and that `this` is in fact the outer object where you log it to the console. Inside the scope of other functions, `this` will of course reference that scope etc.
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      1. USadeneo
    3. CO@jondavidjohn I'm calling the function from my main script. I'm importing it there as a commonJS module. (I've updated my post to reflect that, in case that's causing some issue in some way.) However, I would expect that, upon object creation, the `this` pointer should show me all of my methods...
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