angular.isUndefined & angular.equals in angular 2
<p>I just began to try to migrate from angular 1 to 2, actually from ionic 1 to 2, and one of my first compilation error is that angular.isUndefined and angular.equals aren't resolved.</p>

<p>How should I fix that, any tips?</p>

<pre><code>namespace Utils {

export class Comparator {

    static isEmpty(obj:any):boolean {
        return obj == null || Object.keys(obj).length === 0;
    }

    static isNumberNullOrZero(obj:number):boolean {
        return obj == null || obj === 0;
    }

    static equals(obj1:any, obj2:any):boolean {
        return angular.equals(obj1, obj2); // &lt;== here angular unresolved
    }

    static isStringEmpty(str:string):boolean {
        return !str || 0 === str.length;
    }

    static isStringBlank(str:string):boolean {
        return !str || /^\s*$/.test(str);
    }

    static isBiggerThanZero(num:number):boolean {
        return num != null &amp;&amp; !angular.isUndefined(num) &amp;&amp; num &gt; 0; // &lt;== here angular unresolved
    }

  }
}
</code></pre>