javascript - filtering and rendering of arrays

Question

var data = [{

    label: '分类一',
    value: '0'
}, {
    label: '分类二',
    value: '1'
}, {
    label: '分类三',
    value: '2'
}, {
    label: '分类四',
    value: '3'
}, {
    label: '分类五',
    value: '4'
}, {
    label: '分类六',
    value: '5'
}]

<p class="text">

<span>0</span>
<span>1</span>
<span>2</span>
<span>3</span>
<span>4</span>
<span>5</span>

</p>

Please tell me how to render the corresponding label value in dom based on the value in the data in the simplest way? ? The data is uncertain, there may be more than ten or twenty

in it

Answer 1

The method above can be done, but this is equivalent to registering a variable every time, adding a span node to .text every time, and manipulating the DOM, which causes a lot of overhead! I personally recommend using the following method.

var opText= document.querySelector('.text'),var _text="";
data.forEach(function(item){
    //把每一次遍历的label加上节点，再储存在_text上。
    _text += '<span>'+item.label+'</span>';
});
//最后直接把_text赋值到opText.innerHTML上。
opText.innerHTML=_text ;

Answer 2

var container = document.querySelector('.text')
data.forEach(function(item){
    var span = document.createElement('span')
    span.innerHTML = item.label
    span.setAttribute('value', item.value)
    container.appendChild(span)
})

Answer 3

The methods above are all feasible, but the first two methods have their own advantages and disadvantages in performance under Firefox and Chrome. Now the common practice is to create a new blank document fragment (DocumentFragment).

const $container = document.querySelector('.text');
const fragment = document.createDocumentFragment();
data.map(item => {
    let span = document.createElement("span");
    span.textContent = item;
    fragment.appendChild(span);
});
$container.appendChild(fragment);

Answer 4

var data = [{
    label: '分类一',
    value: '0'
}, {
    label: '分类二',
    value: '1'
}]

// 根据value获取dataList中对应的项
function getLabelByValue(dataList, value) {
  return dataList.find(function (item) {
    return item.value === value // 这里使用的强等，根据情况可选 ==
  })
}

// 省略DOM操作
let label = getLabelByValue(data, '0') // 分类一