var $p = $("p")
$p.css('font-size','40px') //css是原型方法
console.log($p.html()) //html是原型方法
var $div1 = $("#div1")
$div1.css('color','blue') //css是原型方法
console.log($div1.html()) //html是原型方法
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zepto如何使用原型
//空物件
var zepto = {}
zepto.init = function(){
//原始碼中，這裡的處理情況比較複雜。但因為是本次只是針對原型，因此這裡就弱化了
var slice = Array.prototype.slice
var dom = slice.call(document.querySelectorAll(selector))
return zepto.Z(dom,selector)
}
//即使用zepto時候的$
var $ = function(selector){
return zepto.init(selector)
}
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//這就是建構函式
function Z(dom, selector) {
var i, len = dom ? dom.length : 0
for (i = 0; i < len; i++) {
this[i] = dom[i]
}
this.length = len
this.selector = selector || ''
}
zepto.Z = function(dom, selector) {
return new Z(dom, selector)
}
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var wait = function(){
var task = function(){
console.log('執行完成');
}
setTimeout(task,2000)
}
wait();
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新增需求：要在執行完成之後進行某些特別複雜的操作，程式碼可能會很多，而且分好幾步
functionwaitHandle(){
var dtd = $.Deferred(); //建立一個deferred物件
var wait = function(dtd){ // 要求傳入一個deferred物件
var task = function(){
console.log("執行完成");
dtd.resolve(); //表示非同步任務已完成
//dtd.reject() // 表示非同步任務失敗或者出錯
};
setTimeout(task,2000);
return dtd;
}
//注意，這裡已經要有返回值
returnwait(dtd);
}
//使用
var w = waithandle()
w.then(function(){
console.log('ok1');
},function(){
console.log('err2');
})
.then(function(){
console.log('ok2');
},function(){
console.log('err2');
})
//還有w.wait w.fail
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總結：dtd的API可分成兩類，用意不同
第一類：dtd.resolve 、 dtd.reject
第二類：dtd.then、dtd.done、dtd.fail
這兩類應該分開，否則後果嚴重！
可以在上面程式碼中最後執行dtd.reject()試一下後果
使用dtd.promise()
functionwaitHandle(){
var dtd = $.Deferred();
var wait = function(){
var task = function(){
console.log('執行完成');
dtd.resolve();
}
setTimeout(task,2000)
return dtd.promise(); //注意這裡返回的是promise，而不是直接返回deferred物件
}
returnwait(dtd)
}
var w = waitHandle(); //promise物件
$.when(w).then(function(){
console.log('ok1');
},function(){
console.log('err1');
})
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監聽式呼叫：只能被動監聽，不能干預promise的成功和失敗
可以jQuery1.5對ajax的改變舉例
說明如何簡單的封裝、使用deferred
說明promise和Defrred的區別
要想深入瞭解它，就需要知道它的前世今生
Promise的基本使用和原理
基本語法
fucntion loadImg() {
var promise = new Promise(function(resolve,reject) {
var img = document.getElementById("img")
img.onload = function(){
resolve(img)
}
img.onerror = function(){
reject()
}
})
return promise
}
var src = ""
var result = loadImg(src)
result.then(function() {
console.log(1, img.width)
return img
}, fucntion() {
console.log('error 1')
}).then(function(img) {
console.log(1, img.width)
})
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異常捕獲
規定
then只接受一個函式(只接受一個成功的回撥函式)，最後統一用catch捕獲異常
兩種異常情況：
程式邏輯異常
業務之內，reject()等情況
處理方案
在reject("圖片路徑錯誤")中把資訊傳出去，可以通過'.catch()'捕獲
var src = ""
var result = loadImg(src)
result.then(function() {
console.log(1, img.width)
return img
}).then(function(img) {
console.log(1, img.width)
}).catch(function(ex) {
//最後統一捕獲異常
console.log(ex)
})
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多個串聯
var scr1 = 'https://www.imooc.com/static/img/index/logo_new.png';
var result1 = loadImg(src1);
var src2 = 'https://www.imooc.com/static/img/index/logo_new1.png';
var result2 = loadImg(src2);
result1.then(function(img1) {
console.log('第一個圖片載入完成', img1.width);
return result2; //重要
}).then(function(img2) {
console.log('第二個圖片載入完成', img2.width);
}).catch(function(ex) {
console.log(ex);
})
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var div = document.createElement('div');
var item,result = '';
for(item in div){
result += '|' + item;
}
console.log(result);
//瀏覽器預設建立出來的DOM節點，屬性是非常多的
//result
|align|title|lang|translate|dir|dataset|hidden|tabIndex|accessKey|draggable|spellcheck|autocapitalize|contentEditable|isContentEditable|inputMode|offsetParent|offsetTop|offsetLeft|offsetWidth|offsetHeight|style|innerText|outerText|onabort|onblur|oncancel|oncanplay|oncanplaythrough|onchange|onclick|onclose|oncontextmenu|oncuechange|ondblclick|ondrag|ondragend|ondragenter|ondragleave|ondragover|ondragstart|ondrop|ondurationchange|onemptied|onended|onerror|onfocus|oninput|oninvalid|onkeydown|onkeypress|onkeyup|onload|onloadeddata|onloadedmetadata|onloadstart|onmousedown|onmouseenter|onmouseleave|onmousemove|onmouseout|onmouseover|onmouseup|onmousewheel|onpause|onplay|onplaying|onprogress|onratechange|onreset|onresize|onscroll|onseeked|onseeking|onselect|onstalled|onsubmit|onsuspend|ontimeupdate|ontoggle|onvolumechange|onwaiting|onwheel|onauxclick|ongotpointercapture|onlostpointercapture|onpointerdown|onpointermove|onpointerup|onpointercancel|onpointerover|onpointerout|onpointerenter|onpointerleave|nonce|click|focus|blur|namespaceURI|prefix|localName|tagName|id|className|classList|slot|attributes|shadowRoot|assignedSlot|innerHTML|outerHTML|scrollTop|scrollLeft|scrollWidth|scrollHeight|clientTop|clientLeft|clientWidth|clientHeight|attributeStyleMap|onbeforecopy|onbeforecut|onbeforepaste|oncopy|oncut|onpaste|onsearch|onselectstart|previousElementSibling|nextElementSibling|children|firstElementChild|lastElementChild|childElementCount|onwebkitfullscreenchange|onwebkitfullscreenerror|setPointerCapture|releasePointerCapture|hasPointerCapture|hasAttributes|getAttributeNames|getAttribute|getAttributeNS|setAttribute|setAttributeNS|removeAttribute|removeAttributeNS|hasAttribute|hasAttributeNS|toggleAttribute|getAttributeNode|getAttributeNodeNS|setAttributeNode|setAttributeNodeNS|removeAttributeNode|closest|matches|webkitMatchesSelector|attachShadow|getElementsByTagName|getElementsByTagNameNS|getElementsByClassName|insertAdjacentElement|insertAdjacentText|insertAdjacentHTML|requestPointerLock|getClientRects|getBoundingClientRect|scrollIntoView|scrollIntoViewIfNeeded|animate|computedStyleMap|before|after|replaceWith|remove|prepend|append|querySelector|querySelectorAll|webkitRequestFullScreen|webkitRequestFullscreen|scroll|scrollTo|scrollBy|createShadowRoot|getDestinationInsertionPoints|ELEMENT_NODE|ATTRIBUTE_NODE|TEXT_NODE|CDATA_SECTION_NODE|ENTITY_REFERENCE_NODE|ENTITY_NODE|PROCESSING_INSTRUCTION_NODE|COMMENT_NODE|DOCUMENT_NODE|DOCUMENT_TYPE_NODE|DOCUMENT_FRAGMENT_NODE|NOTATION_NODE|DOCUMENT_POSITION_DISCONNECTED|DOCUMENT_POSITION_PRECEDING|DOCUMENT_POSITION_FOLLOWING|DOCUMENT_POSITION_CONTAINS|DOCUMENT_POSITION_CONTAINED_BY|DOCUMENT_POSITION_IMPLEMENTATION_SPECIFIC|nodeType|nodeName|baseURI|isConnected|ownerDocument|parentNode|parentElement|childNodes|firstChild|lastChild|previousSibling|nextSibling|nodeValue|textContent|hasChildNodes|getRootNode|normalize|cloneNode|isEqualNode|isSameNode|compareDocumentPosition|contains|lookupPrefix|lookupNamespaceURI|isDefaultNamespace|insertBefore|appendChild|replaceChild|removeChild|addEventListener|removeEventListener|dispatchEvent
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vdom如何應用，核心API是什麼
介紹snabbdom
一個實現vdom的庫,vue升級2.0借鑑了snabbdom的演算法
var container = document.getElementById('container')
var vnode = h('div#container.two.classes', { on: { click: someFn } }, [
h('span', { style: { fontWeight: 'bold' }, 'This is bold' }),
'and this is just normal text',
h('a', { props: { href: '/foo' } }, 'I\'ll take you places')
])
//patch into empty DOM element - this modifies the DOM as a side effect
patch(container, vnode)
var newVnode = h('div#container.two.classes', { on: { click: anotherEventHandle } }, [
h('span', { style: { fontWeight: 'normal', fontStyle: 'italic' } }, 'this is now italic type'),
'and this is still just normal text',
h('a', { props: { href: '/bar' } }, 'I\'ll take you places')
])
//send `patch` invocation
patch(vnode, newVnode); //Snabbdom efficiently updates the old view to the new state
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<ul id = "list">
<li class='item'>Item 1</li>
</ul>
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簡單實現演算法
function createElement(vnode) {
var tag = vnode.tag;
var attrs = vnode.attrs || {};
var children = vnode.children || [];
if (!tag) {
return null
}
//建立元素
var elem = document.createElement(tag);
//屬性
var attrName;
for (attrName in atts) {
if (attrs.hasOwnProperty(attrName)) {
elem.setAttribute(attrName, attrs[attrName])
}
}
//子元素
children.array.forEach(childVnode => {
elem.appendChild(createElement(childVnode))
});
return elem;
}
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//vm._l
function renderList(val,render) {
var ret, i, l, keys, key;
if (Array.isArray(val) || typeof val === 'string') {
ret = new Array(val.length);
for (i = 0, l = val.length; i < l; i++) {
ret[i] = render(val[i], i);
}
} elseif (typeof val === 'number') {
ret = new Array(val);
for (i = 0; i < val; i++) {
ret[i] = render(i + 1, i);
}
} elseif (isObject(val)) {
keys = Object.keys(val);
ret = new Array(keys.length);
for (i = 0, l = keys.length; i < l; i++) {
key = keys[i];
ret[i] = render(val[key], key, i);
}
}
if (isDef(ret)) {
(ret)._isVList = true;
}
return ret
}
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import Todo from './components/todo/index.js';
class App extends Component {
render() {
return (
<div className="App">
<Todo></Todo>
</div>
);
}
}
export default App;
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src => components => todo
import React, { Component } from 'react'
class Todo extends Component {
constructor(props) {
super(props)
}
render() {
return (
<p> this is todo component </p>
)
}
}
export default Todo
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todolist Demo2
list => todo => index.js
import React, { Component } from 'react'
class List extends Component{
constructor(props){
super(props)
}
render() {
const list = this.props.data
return (
<ul>
{
list.map((item,index) =>{
return <li key={index}>{item}</li>
})
}
</ul>
)
}
}
export default List
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必須加key
todo.js
import React, { Component } from 'react'
import List from './list/index.js';
import Input from './input/index.js';
class Todo extends Component {
constructor(props) {
super(props)
this.state = {
list:[]
}
}
render() {
return (
<div>
<Input addTitle={this.addTitle.bind(this)}/>
<List data={this.state.list} />
</div>
)
}
//主動新增list
addTitle(title){
const currentList = this.state.list //獲取當前list
this.setState(
{
list:currentList.concat(title)
}
)
}
}
export default Todo
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