Angular.js question

/*
 * The following code snippet runs in an angular controller body.
 * It tries to convert a blob object "data" into data URL and bind the result to the scope.
 * Fix it so that $scope.data will make UI change as expected.
 */
/* global angular, data, FileReader */
angular.module('xxx').controller('Ctrl', ['$scope', function ($scope) {
var reader = new FileReader();
reader.onload = function (event) {
$scope.data = event.target.result;
    };
reader.readAsDataURL(data);
}]);

bind, call, apply diff

/*
 * Please describe different of bind, call, apply.
 */

Javascript getElementById

/*
 * Fix the following code snippet to make it work.
 * You can only modify line 7.
 * (Assume that <div id="page1"></div> exists)
 */
var g = document.getElementById;

g('page1').innerHTML = 'Hello World!';

Question timeout

/*
 * Discuss the possible console output results for this code snippet.
 * The "doSomething" function accepts a callback function as the input argument,
 * but whether it is synchronus or asynchronus remains unknown.
 */

/* global doSomething */

console.log('hello 1');

setTimeout(function () {
    console.log('hello 2');
}, 1);

console.log('hello 3');

doSomething(function (result) {
    console.log('doSomething done');
});

setTimeout(function () {
    console.log('hello 4');
}, 0);

console.log('hello 5');

React.js, Angular.js different

/*
 * Please describe different of React.js, Angular.js.
 * Which one you will choice.
 */