【前端】常用总结（一）
阅读目录
一、canvas截图
二、分组间元素拖动
三、占位符交互效果
四、导出Excel/Zip文件
一、canvas截图
1 需求
页面内的某块容器截图，截取的图片需要去除不需要的元素
2 canvas实现
- canvas官网: http://html2canvas.hertzen.com/
//截图
function capturePicture(){
//修改全局视图样式 借助vue实现可以在此处先把页面上不需要截取元素隐藏掉
//this.capture_status = true;
//base64转blob
function dataURIToBlob(dataURI) {
var binStr = atob(dataURI.split(',')[1]),
len = binStr.length,
arr = new Uint8Array(len);
for (var i = 0; i < len; i++) {
arr[i] = binStr.charCodeAt(i);
}
let blobs = new Blob([arr]);
return blobs;
}
function _fixType(type) {
type = type.toLowerCase().replace(/jpg/i, 'jpeg');
let r = type.match(/png|jpeg|bmp|gif/)[0];
return 'image/' + r;
}
//唤起浏览器下载
function fileDownload(dataUrl) {
let aLink = document.createElement('a');
aLink.style.display = 'none';
aLink.href = URL.createObjectURL(dataURIToBlob(dataUrl));
aLink.download = `${formatTimeToYMD(getNowTime())}项目统计.jpg`; //图片名称
// 触发点击-然后移除
document.body.appendChild(aLink);
aLink.click();
document.body.removeChild(aLink);
}
setTimeout(()=>{ //这里加等待时间是为了确保上面设置的页面元素改变之后在截取
const ele = document.getElementById("jira-container"); //截图容器
const config = {
allowTaint: true,
scale: 1
};
html2canvas(ele, config).then(canvas => {
var type = 'jpg';
var imgData = canvas.toDataURL(type); //canvas转换为图片
// 加工image data，替换mime type，方便以后唤起浏览器下载
imgData = imgData.replace(_fixType(type), 'image/octet-stream');
fileDownload(imgData);
this.capture_status = false;
})
}, 300)
},
3 问题
截图的图片如果超出了屏幕大小，请滚动到页面最上部分截取，否则会有截取信息缺失，原因暂时不详。
二、分组间元素拖动
1 需求
多个分组之间实现元素拖动
1.1 例子
分组a: [{"name": "vue.draggable","order": 1,"fixed": false},{"name": "draggable","order": 2,"fixed": false}]
分组b: [{"name": "vue.draggable","order": 3,"fixed": false},{"name": "draggable","order": 4,"fixed": false}]
实现a,b中的元素可以通过拖拽DOM改变
2 Vue.Draggable实现
2.1 html
<draggable
class="dragArea list-group"
:list="list_a" //放入
:clone="clone" //设置后按住ctrl拖拽会复制一行
:group="{ name: 'people', pull: pullFunction }" //name：分组名称， pull：拖动时回调函数
@start="start" //开始拖拽的时候回调函数
>
<div v-for="(item, index) in list_a"></div>
</draggable>
<draggable class="dragArea list-group" :clone="clone" :list="list_b" group="people"> //需要指定group所属分组
<div v-for="(item, index) in list_b"></div>
</draggable>
2.2 js
data() {
return {
controlOnStart: true,
}
}
methods: {
clone(args) {
return JSON.parse(JSON.stringify(args))
},
pullFunction() {
return this.controlOnStart ? "clone" : true;
},
start({ originalEvent }) {
this.controlOnStart = originalEvent.ctrlKey; //是否按ctrl键
},
}
3 问题
假如组内元素是可以输入的，常用操作移动鼠标拉选内容就会很不方便。
三、占位符交互效果
1 需求
Material Design规范中占位符交互效果,实现修改用户名
2 实现
2.1 html
<div class="input-box">
<div class="input-outline-x">
<input class="input-control input-outline" placeholder="新用户名称" v-model="user_info.user_name"/>
<label class="input-label">新用户名称</label>
<span class="span-desc">4-30个字符</span>
</div>
<div class="input-box-button">
<el-button type="primary" size="small" @click="submit">确 定</el-button> //修改操作
<el-button size="small" @click="activeName=''">取 消</el-button>
</div>
</div>
2.2 css
.input-outline-x{
margin-top: 10px;
width: -moz-fit-content;
width: fit-content;
position: relative;
}
.input-fill-x {
border-bottom: 1px solid #d0d0d5;
}
.input-fill-x::after {
content: '';
position: absolute;
border-bottom: 2px solid #2486ff;
left: 0; right: 0; bottom: -1px;
transform: scaleX(0);
transition: transform .25s;
}
.input-fill-x:focus-within::after {
transform: scaleX(1);
}
3 优势
借助CSS placeholder-shown伪类，纯CSS，无任何JS，实现这样的占位符交互效果。
四、导出Excel/Zip文件
1.导出excel
1.1导出代码
import XLSX from 'xlsx'
function export_json_to_excel({
multiHeader = [],
header,
data,
filename,
merges = [],
autoWidth = true,
bookType= 'xlsx'
} = {}) {
/* original data */
filename = filename || 'excel-list'
data = [...data]
data.unshift(header);
for (let i = multiHeader.length-1; i > -1; i--) {
data.unshift(multiHeader[i])
}
var ws_name = "SheetJS";
var wb = new Workbook(),
ws = sheet_from_array_of_arrays(data);
if (merges.length > 0) {
if (!ws['!merges']) ws['!merges'] = [];
merges.forEach(item => {
ws['!merges'].push(XLSX.utils.decode_range(item))
})
}
if (autoWidth) {
/*设置worksheet每列的最大宽度*/
const colWidth = data.map(row => row.map(val => {
/*先判断是否为null/undefined*/
if (val == null) {
return {
'wch': 10
};
}
/*再判断是否为中文*/
else if (val.toString().charCodeAt(0) > 255) {
return {
'wch': val.toString().length * 2
};
} else {
return {
'wch': val.toString().length
};
}
}))
/*以第一行为初始值*/
let result = colWidth[0];
for (let i = 1; i < colWidth.length; i++) {
for (let j = 0; j < colWidth[i].length; j++) {
if (result[j]['wch'] < colWidth[i][j]['wch']) {
result[j]['wch'] = colWidth[i][j]['wch'];
}
}
}
ws['!cols'] = result;
}
/* add worksheet to workbook */
wb.SheetNames.push(ws_name);
wb.Sheets[ws_name] = ws;
var wbout = XLSX.write(wb, {
bookType: bookType,
bookSST: false,
type: 'binary'
});
saveAs(new Blob([s2ab(wbout)], {
type: "application/octet-stream"
}), `${filename}.${bookType}`);
}
1.2使用
const data = [{"name": "dc", "arg": 10}]
//格式化数据，将data数据转化成[["dc", 10], ]
formatJson(filterVal, jsonData) {
return jsonData.map(v => filterVal.map(j => {
return v[j]
}))
}
//
export_json_to_excel.then(excel => {
const tHeader = ['姓名', '年龄']
const filterVal = ['name', 'arg']
const data = formatJson(filterVal, data)
excel.export_json_to_excel({
header: tHeader,
data,
filename: '姓名'
})
})
2.导出多sheet页excel
2.1导出代码
import XLSX from 'xlsx'
//数据写入sheet页对象
function export_write_to_sheet({
multiHeader = [],
header,
data,
merges = [],
autoWidth = false,
} = {}) {
/* original data */
data = [...data]
data.unshift(header);
for (let i = multiHeader.length-1; i > -1; i--) {
data.unshift(multiHeader[i])
}
var ws = sheet_from_array_of_arrays(data);
if (merges.length > 0) {
if (!ws['!merges']) ws['!merges'] = [];
merges.forEach(item => {
ws['!merges'].push(XLSX.utils.decode_range(item))
})
}
return ws
}
// sheet页对象信息写入excel
function writer_sheet_data_to_excle(filename, data) {
var wb = new Workbook()
for(let i=0;i<data.length;i++){
/* add worksheet to workbook */
wb.SheetNames.push(data[i][0]);
wb.Sheets[data[i][0]] = data[i][1];
}
// filename = filename || 'excel-list';
var wbout = XLSX.write(wb, {
bookType: 'xlsx',
bookSST: false,
type: 'binary'
});
saveAs(new Blob([s2ab(wbout)], {
type: "application/octet-stream"
}), `${filename}.xlsx`);
}
2.2使用
const data1 = [{"name": "dc", "arg": 10}]
const data2 = [{"name1": "dz", "arg1": 15}]
//格式化数据
formatJson(filterVal, jsonData) {
return jsonData.map(v => filterVal.map(j => {
return v[j]
}))
const t1Filter = ['name', 'arg'];
const t2Filter = ['name1', 'arg1'];
const t1Header = ['姓名', '年龄']
const t2Header = ['姓名1', '年龄1']
let record_data = [];
// 格式化数据
const fdata1 = formatJson(t1Filter, data1);
const fdata2 = formatJson(t2Filter, data2);
// 数据写入sheet页对象
const ws1 = excel.export_write_to_sheet({ header: t1Header, data:fdata1})
const ws2 = excel.export_write_to_sheet({ header: t2Header, data:fdata2})
record_data.push(['sheet1', ws1]);
record_data.push(['sheet2', ws2]);
# 循环添加sheet对象信息
excel.writer_sheet_data_to_excle('多sheet页', record_data)
3.导出Zip
require('script-loader!file-saver');
import JSZip from 'jszip'
// 导出zip压缩文件
export function export_txt_to_zip(th, jsonData, txtName, zipName) {
const zip = new JSZip()
const txt_name = txtName || 'file'
const zip_name = zipName || 'file'
const data = jsonData
let txtData = `${th}\r\n`
data.forEach((row) => {
let tempStr = ''
tempStr = row.toString()
txtData += `${tempStr}\r\n`
})
zip.file(`${txt_name}.txt`, txtData)
zip.generateAsync({
type: "blob"
}).then((blob) => {
saveAs(blob, `${zip_name}.zip`)
}, (err) => {
alert('导出失败')
})
}
