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提交练习4 #154

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12 changes: 8 additions & 4 deletions test/test.js
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Original file line number Diff line number Diff line change
Expand Up @@ -4,7 +4,8 @@ describe('this', function () {
say: function () {
setTimeout(() => {
// this 是什么？想想为什么？
this.should.equal(null)
// 箭头函数的this是函数调用时所处的上下文，又因为say是作为obj的属性调用的，故为obj
this.should.equal(obj)
done()
}, 0)
}
Expand All @@ -15,7 +16,8 @@ describe('this', function () {
it('global', function () {
function test() {
// this 是什么？想想为什么？
this.should.equal(null)
// 默认绑定在window上，node环境下为global
this.should.equal(global)
}
test()
})
Expand All @@ -26,7 +28,8 @@ describe('this', function () {
say: function () {
function _say() {
// this 是什么？想想为什么？
this.should.equal(null)
// 显示绑定在obj上，obj为undefined，则绑定在global下
this.should.equal(global)
}
return _say.bind(obj)
}()
Expand All @@ -39,7 +42,8 @@ describe('this', function () {
obj.say = function () {
function _say() {
// this 是什么？想想为什么？
this.should.equal(null)
// 显示绑定在obj上
this.should.equal(obj)
}
return _say.bind(obj)
}()
Expand Down