通用封装函数——四则运算

# 加法

代码语言：javascript复制

add = (v1, v2) => {
    v1  = '';
    v2  = '';
    let r1, r2;
    try {
        r1 = v1.toString().split('.')[1].length;
    } catch (e) {
        r1 = 0;
    }
    try {
        r2 = v2.toString().split('.')[1].length;
    } catch (e) {
        r2 = 0;
    }
    const m = 10 ** Math.max(r1, r2);
    return (mul(v1, m)   mul(v2, m)) / m;
};

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# 减法

代码语言：javascript复制

sub = (v1, v2) => {
    return add(v1, -v2);
};

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# 乘法

代码语言：javascript复制

mul = (v1, v2) => {
    v1  = '';
    v2  = '';
    let m = 0;
    const s1 = v1.toString();
    const s2 = v2.toString();
    try {
        m  = s1.split('.')[1].length;
    } catch (e) {
    }
    try {
        m  = s2.split('.')[1].length;
    } catch (e) {
    }
    return (Number(s1.replace('.', '')) * Number(s2.replace('.', ''))) / 10 ** m;
};

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# 除法

代码语言：javascript复制

div = (v1, v2) => {
    v1  = '';
    v2  = '';
    let t1 = 0,
        t2 = 0;
    try {
        t1 = v1.toString().split('.')[1].length;
    } catch (e) {
    }
    try {
        t2 = v2.toString().split('.')[1].length;
    } catch (e) {
    }
    const r1 = Number(v1.toString().replace('.', ''));
    const r2 = Number(v2.toString().replace('.', ''));
    return (r1 / r2) * 10 ** (t2 - t1);
};

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# 其它

# 正数向上取整

代码语言：javascript复制

// 3453.1 → 4000
ceil = v1 => {
    v1 = Math.ceil(v1);
    if (v1 === 0) return v1;
    let num = Math.pow(10, v1.toString().length - 1);
    return mul(Math.ceil(div(v1, num)), num);
};

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# 首字母大写

代码语言：javascript复制

// github → Github
firstUpper = str => {
	return str.charAt(0).toUpperCase()   str.slice(1);
};

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# 对象 Key Value 反转

代码语言：javascript复制

obj_flip = obj => {
    return Object.keys(obj).reduce((acc, key) => {
        acc[obj[key]] = key;
        return acc;
    }, {});
};

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key 对象

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