82个常规的前端JavaScript方法封装（71~82）
发表于：2021-12-05 17:54:35浏览：2129次
本篇文章主要介绍的是一些常用的前端JavaScript方法封装，原生dom操作，判断图片加载完成，音频加载完成操作，光标所在位置插入字符，图片地址转base64等，自己收集整理以便后期使用，需要的朋友可以阅读收藏。
71、原生dom操作
const dom = {
$: function(selector) {
let type = selector.substring(0, 1)
if (type === '#') {
if (document.querySelecotor) return document.querySelector(selector)
return document.getElementById(selector.substring(1))
} else if (type === '.') {
if (document.querySelecotorAll) return document.querySelectorAll(selector)
return document.getElementsByClassName(selector.substring(1))
} else {
return document['querySelectorAll' ? 'querySelectorAll' : 'getElementsByTagName'](selector)
}
},
hasClass: function(ele, name) { /* 检测类名 */
return ele.className.match(new RegExp('(\s|^)' + name + '(\s|$)'))
},
addClass: function(ele, name) { /* 添加类名 */
if (!this.hasClass(ele, name)) ele.className += ' ' + name
},
removeClass: function(ele, name) { /* 删除类名 */
if (this.hasClass(ele, name)) {
let reg = new RegExp('(\s|^)' + name + '(\s|$)')
ele.className = ele.className.replace(reg, '')
}
},
replaceClass: function(ele, newName, oldName) { /* 替换类名 */
this.removeClass(ele, oldName)
this.addClass(ele, newName)
},
siblings: function(ele) { /* 获取兄弟节点 */
console.log(ele.parentNode)
let chid = ele.parentNode.children,
eleMatch = []
for (let i = 0, len = chid.length; i < len; i++) {
if (chid[i] !== ele) {
eleMatch.push(chid[i])
}
}
return eleMatch
},
getByStyle: function(obj, name) { /* 获取行间样式属性 */
if (obj.currentStyle) {
return obj.currentStyle[name]
} else {
return getComputedStyle(obj, false)[name]
}
},
domToStirng: function(htmlDOM) { /* DOM转字符串 */
var div = document.createElement('div')
div.appendChild(htmlDOM)
return div.innerHTML
},
stringToDom: function(htmlString) { /* 字符串转DOM */
var div = document.createElement('div')
div.innerHTML = htmlString
return div.children[0]
}
}72、判断图片加载完成
const imgLoadAll = function(arr, callback) { // 图片加载
let arrImg = [] for (let i = 0; i < arr.length; i++) { let img = new Image()
img.src = arr[i]
img.onload = function() {
arrImg.push(this) if (arrImg.length == arr.length) {
callback && callback()
}
}
}
}73、音频加载完成操作
const loadAudio = function(src, callback) { // 音频加载
var audio = new Audio(src)
audio.onloadedmetadata = callback
audio.src = src
}74、光标所在位置插入字符
const insertAtCursor = function(dom, val) { // 光标所在位置插入字符
if (document.selection) {
dom.focus() let sel = document.selection.createRange()
sel.text = val
sel.select()
} else if (dom.selectionStart || dom.selectionStart == '0') { let startPos = dom.selectionStart let endPos = dom.selectionEnd let restoreTop = dom.scrollTop
dom.value = dom.value.substring(0, startPos) + val + dom.value.substring(endPos, dom.value.length) if (restoreTop > 0) {
dom.scrollTop = restoreTop
}
dom.focus()
dom.selectionStart = startPos + val.length
dom.selectionEnd = startPos + val.length
} else {
dom.value += val
dom.focus()
}
}75、图片地址转base64
const getBase64 = function(img) { //传入图片路径，返回base64，使用getBase64(url).then(function(base64){},function(err){});
let getBase64Image = function(img, width, height) { //width、height调用时传入具体像素值，控制大小,不传则默认图像大小
let canvas = document.createElement("canvas");
canvas.width = width ? width : img.width;
canvas.height = height ? height : img.height; let ctx = canvas.getContext("2d");
ctx.drawImage(img, 0, 0, canvas.width, canvas.height); let dataURL = canvas.toDataURL(); return dataURL;
} let image = new Image();
image.crossOrigin = '';
image.src = img; let deferred = $.Deferred(); if (img) {
image.onload = function() {
deferred.resolve(getBase64Image(image));
} return deferred.promise();
}
}76、base64图片下载功能
const downloadFile = function(base64, fileName) { //base64图片下载功能
let base64ToBlob = function(code) { let parts = code.split(';base64,'); let contentType = parts[0].split(':')[1]; let raw = window.atob(parts[1]); let rawLength = raw.length; let uInt8Array = new Uint8Array(rawLength); for (let i = 0; i < rawLength; ++i) {
uInt8Array[i] = raw.charCodeAt(i);
} return new Blob([uInt8Array], { type: contentType
});
}; let aLink = document.createElement('a'); let blob = base64ToBlob(base64); //new Blob([content]);
let evt = document.createEvent("HTMLEvents");
evt.initEvent("click", true, true); //initEvent不加后两个参数在FF下会报错 事件类型，是否冒泡，是否阻止浏览器的默认行为
aLink.download = fileName;
aLink.href = URL.createObjectURL(blob);
aLink.click();
}77、浏览器是否支持webP格式图片
const isSupportWebP = function() { //判断浏览器是否支持webP格式图片
return !![].map && document.createElement('canvas').toDataURL('image/webp').indexOf('data:image/webp') == 0;
}78、url参数转对象
const parseQueryString = function(url) { //url参数转对象
url = !url ? window.location.href : url; if (url.indexOf('?') === -1) { return {};
} let search = url[0] === '?' ? url.substr(1) : url.substring(url.lastIndexOf('?') + 1); if (search === '') { return {};
}
search = search.split('&'); let query = {}; for (let i = 0; i < search.length; i++) { let pair = search[i].split('=');
query[decodeURIComponent(pair[0])] = decodeURIComponent(pair[1] || '');
} return query;
}79、对象序列化【对象转url参数】
const stringfyQueryString = function(obj) { //对象序列化【对象转url参数】
if (!obj) return '';
let pairs = [];
for (let key in obj) {
let value = obj[key];
if (value instanceof Array) {
for (let i = 0; i < value.length; ++i) {
pairs.push(encodeURIComponent(key + '[' + i + ']') + '=' + encodeURIComponent(value[i]));
}
continue;
}
pairs.push(encodeURIComponent(key) + '=' + encodeURIComponent(obj[key]));
}
return pairs.join('&');
}80、H5软键盘缩回、弹起回调
const h5Resize = function(downCb, upCb) { //当软件键盘弹起会改变当前 window.innerHeight，监听这个值变化 [downCb 当软键盘弹起后，缩回的回调,upCb 当软键盘弹起的回调]
var clientHeight = window.innerHeight;
downCb = typeof downCb === 'function' ? downCb : function() {}
upCb = typeof upCb === 'function' ? upCb : function() {} window.addEventListener('resize', () => { var height = window.innerHeight; if (height === clientHeight) {
downCb();
} if (height < clientHeight) {
upCb();
}
});
}81、函数防抖
const debounce = function(func, wait, immediate) { //函数防抖[func 函数,wait 延迟执行毫秒数,immediate true 表立即执行,false 表非立即执行,立即执行是触发事件后函数会立即执行，然后n秒内不触发事件才能继续执行函数的效果]
let timeout; return function() { let context = this; let args = arguments; if (timeout) clearTimeout(timeout); if (immediate) { var callNow = !timeout;
timeout = setTimeout(() => {
timeout = null;
}, wait) if (callNow) func.apply(context, args)
} else {
timeout = setTimeout(function() {
func.apply(context, args)
}, wait);
}
}
}82、函数节流
const throttle = function(func, wait ,type) { //函数节流 [func 函数 wait 延迟执行毫秒数 type 1 表时间戳版，2 表定时器版]
if(type===1){ let previous = 0;
}else if(type===2){ let timeout;
} return function() { let context = this; let args = arguments; if(type===1){ let now = Date.now(); if (now - previous > wait) {
func.apply(context, args);
previous = now;
}
}else if(type===2){ if (!timeout) {
timeout = setTimeout(() => {
timeout = null;
func.apply(context, args)
}, wait)
}
}
} 