It looks like the library is actually deprecated.
I’ve found another library that implements sha-256,
https://www.npmjs.com/package/jssha
npm install jssha --save
npm install @types/jssha --save-dev
import { Component } from '@angular/core';
import jsSHA from 'jssha'
import { NavController } from 'ionic-angular';
@Component({
selector: 'page-home',
templateUrl: 'home.html'
})
export class HomePage {
constructor(public navCtrl: NavController) {
let shaObj = new jsSHA("SHA-256", "TEXT");
shaObj.update("This is a test");
let hash = shaObj.getHash("HEX");
console.log(hash)
}
}