Edit in JSFiddle

// Mock.mock( rurl, rtype, function(options) )
Mock.mock(/\.json/, 'get', function(options) {
    return options.type
})
Mock.mock(/\.json/, 'post', function(options) {
    return options.type
})

$.ajax({
    url: 'hello.json',
    type: 'get',
    dataType: 'json'
}).done(function (data, status, jqXHR) {
    $('<pre>').text(JSON.stringify(data, null, 4))
        .appendTo('body')
})

$.ajax({
    url: 'hello.json',
    type: 'post',
    dataType: 'json'
}).done(function (data, status, jqXHR) {
    $('<pre>').text(JSON.stringify(data, null, 4))
        .appendTo('body')
})

<!-- （必选）加载 Mock -->
<script src="http://mockjs.com/dist/mock.js"></script>