Comments (2)
请问老师,下面这个mvvm demo的例子中:
Object.defineProperty的get方法,怎么直接返回model.text的值 (就是不用另外设置一个变量randomStr,而是直接返回被设置的新的值);如果不写get方法,又会是undefined
<!DOCTYPE html>
<html>
<div id="container">
<!-- view 部分 (model.text表示取model.text的数据) -->
<p id="p" data="{{model.text}}"><p>
</div>
<script>
/** model 部分 **/
let model = {
text: '',
}
// 监听model.text数据变化(重点)
Object.defineProperty(model, 'text', {
set: (value) => {
// model.text变化,新的值是value
render() // 重新render p 元素 (把Model的数据同步到View显示出来)
},
// get: () => model.text //(死循环)
get: () => randomStr
})
// 模拟数据变化(每秒)
let randomStr = ''
setInterval(() => {
// 设置一个随机数
randomStr = Math.floor(Math.random() * 10000) + ''
model.text = randomStr
}, 1000)
// DIY 一个render方法:模拟渲染p元素(根据p元素的属性data的模板语法)
const render = () => {
const p = document.querySelector('#container p');
const expression = /\{\{([^{}]*)\}\}/.exec(p.getAttribute('data'))[1]; // model.text
// 根据模板变量,修改p的文本
p.innerText = eval(expression);
}
</script>
</html>
from 2019.03.
(function (model, name , value){
Object.defineProperty(model, name, {
set: (newValue) => {
value = newValue;
render()
return value;
},
get: () => {
return value
}
})
})(model,'text');
Object.defineProperty 改成这个部分,不然一直 mode.text 会进入一直 get 死循环
from 2019.03.
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