How to use look-at feature in Ar.js programatically

I am trying to use the look-at feature of Ar.js dynamically through js. But for some reason, the 3d-object is not looking out of the screen.

Solution

Answering the topic

You can set the look-at component using javascript, by adding it to any a-frame entity:

// using an existing entity as a target
entity.setAttribute("look-at", "#selector");
// using a Vector3 position as target 
entity.setAttribute("look-at", {x: 0, y: 0, z: 0})

Answering this specific case

The look-at component (and the used by it lookAt method) assume, that the model is orented towards the z-axis.

The duck model is oriented towards the x axis. If it's possible, reorient the model in a 3D modelling software like blender. If not, then you can use a parent node to reorient it:

<!-- Parent node will look at the user--/>
<a-entity look-at="[camera]">
    <!-- Child node with the rotation offset--/>
    <a-entity rotation="0 -90 0" gltf-model ....>

Check it out in this glitch
If there are more models, you can create a rotation offset array, and apply it to the [gltf-model] node each time you load a new model.

The <a-camera> already contains a camera. To change its properties just use the <a-camera> attributes:

<a-camera fov="60" ....></a-camera>