几个常用的JavaScript工具函数

file转base64

/**
* @param { * } file 图片文件
*/
    export const fileToBase64 = file => {
        let reader = new FileReader();
        reader.readAsDataURL(file);
        reader.onload = function (e) {
            return e.target.result
        };
    };

匹配电子邮件地址

// 匹配电子邮件地址
let isEmailAddress = val => {
    return /^[\w-]+(\.[\w-]+)*@[\w-]+(\.[\w-]+)+$/.test(val) || /w+([-+.]w+)*@w+([-.]w+)*.w+([-.]w+)*/.test(val);
};
console.log(isEmailAddress('Acs')) //false
console.log(isEmailAddress('133@qq.com')) //true

匹配正整数

// 匹配正整数
let isPositiveNum = val => {
    return /^[1-9]d*$/.test(val);
};
console.log(isPositiveNum(9)) //true
console.log(isPositiveNum(2.2)) //false

匹配整数

// 匹配整数
let isInteger = val => {
    return /^(-|\+)?\d+$/.test(val);
};
console.log(isInteger(-9)) //true
console.log(isInteger(2.2)) //false

匹配由 26 个英文字母组成的字符串

//匹配由 26 个英文字母组成的字符串
let isAZaz = val => {
    return /^[A-Za-z]+$/.test(val);
};
console.log(isAZaz('122a')) //false
console.log(isAZaz('abc')) //true

获取窗口可视范围的高度

export function getClientHeight() {
    let clientHeight = 0;
    if (document.body.clientHeight && document.documentElement.clientHeight) {
        clientHeight = (document.body.clientHeight < document.documentElement.clientHeight) ? document.body.clientHeight : document.documentElement.clientHeight;
    }
    else {
        clientHeight = (document.body.clientHeight > document.documentElement.clientHeight) ? document.body.clientHeight : document.documentElement.clientHeight;
    }
    return clientHeight;
}

获取滚动条距顶部高度

export function getPageScrollTop() {
    let a = document;
    return a.documentElement.scrollTop || a.body.scrollTop;
}

开启全屏

/**
* @param {*} element
*/
    export function launchFullscreen(element) {
        if (element.requestFullscreen) {
            element.requestFullscreen()
        } else if (element.mozRequestFullScreen) {
            element.mozRequestFullScreen()
        } else if (element.msRequestFullscreen) {
            element.msRequestFullscreen()
        } else if (element.webkitRequestFullscreen) {
            element.webkitRequestFullScreen()
        }
    }

关闭全屏

export function exitFullscreen() {
    if (document.exitFullscreen) {
        document.exitFullscreen()
    } else if (document.msExitFullscreen) {
        document.msExitFullscreen()
    } else if (document.mozCancelFullScreen) {
        document.mozCancelFullScreen()
    } else if (document.webkitExitFullscreen) {
        document.webkitExitFullscreen()
    }
}

截取字符串并加身略号

export function subText(str, length) {
    if (str.length === 0) {
        return '';
    }
    if (str.length > length) {
        return str.substr(0, length) + "...";
    } else {
        return str;
    }
}