How I can pass a value to a controller using a component?

Question

I'm trying to pass a value to my controller trough my component but im still getting this undefined message. Am I missing something?

myhtml.html

<my-component item="value1"></my-component>
<my-component item="value2"></my-component>
<my-component item="value3"></my-component>

mycomponent.js

angular
    .module('mycomponent.component', [
        'mycomponent.controller'
    ])
    .component('myComponent', {
        templateUrl: 'components/mycomp/mycomp.component.html',
        controller: 'ComponentController',
        controllerAs: 'componentVM',
        replace: true,
        bindings: {
            item: '='
        }
    });

mycontroller.js

angular
    .module('mycomponent.controller', [])
    .controller('ComponentController', ComponentController);

    ComponentController.$inject = [];

    function ComponentController() {
        var vm = this;
        console.log('item value> ' + vm.item); // This is got undefined :(
    }

Answer 1

As suggested in the comments by @mhodges put all your logic inside the $onInit hook. $onInit is triggered as part of the component life cycle when all your bindings are initialized.

var self = this;
self.$onInit = function(){
  console.log('item value> ' + self.item);
}

Back to your code, if value1 is a primitive type you should be using a single way binding @ (primitive type cannot use a two way binding as they aren't references)

bindings: {
  item: '@'
}

<my-component item="value1"></my-component>

In a scenario where item is an object, to decouple the component from the outer environment it would be better to use a one way binding < ,

bindings: {
  item: '<'
}

this would even follow the guidelines of Angular > 1.5 that aim to a component based architecture.

From Angular 1.5 doc:

Inputs should be using < and @ bindings. The < symbol denotes one-way bindings which are available since 1.5. The difference to = is that the bound properties in the component scope are not watched, which means if you assign a new value to the property in the component scope, it will not update the parent scope

https://docs.angularjs.org/guide/component