“它"是什么意思?这段代码中的功能是什么?

I'm hoping somebody could explain to me what "it" does (is used for) in AngularJS or just plain JavaScript (I'm not sure if it's specific to Angular). This, turns out, is a difficult thing to Google for, being named "it" and all. I've seen it used throughout the AngularJS docs. I'll give you an example from the ngShow page (it's code to hide/show a div containing a thumbs up or thumbs down).

var thumbsUp = element(by.css('span.glyphicon-thumbs-up'));
var thumbsDown = element(by.css('span.glyphicon-thumbs-down'));

it('should check ng-show / ng-hide', function() {
  expect(thumbsUp.isDisplayed()).toBeFalsy();
  expect(thumbsDown.isDisplayed()).toBeTruthy();

  element(by.model('checked')).click();

  expect(thumbsUp.isDisplayed()).toBeTruthy();
  expect(thumbsDown.isDisplayed()).toBeFalsy();
});

推荐答案

参见 Jasmine 测试框架.

it(...) 函数定义了一个测试用例(又名规范").

describe("A suite", function() {
  it("contains spec with an expectation", function() {
    expect(true).toBe(true);
  });
});