//检测是否为数字
let num = (a) => {
if(a != null && a.toString() != "") {
let r = /^-?(0|[1-9]+\d*|[1-9]+\d*\.\d+|0\.\d+)$/;
if(r.test(a.toString())) {
return true;
}
}
return false;
}
//加法
let plus = (a, b) => {
if(!num(a) || !num(b)) {
return null;
}
let c, d, m;
try {
c = a.toString().split(".")[1].length;
} catch(e) {
c = 0;
}
try {
d = b.toString().split(".")[1].length;
} catch(e) {
d = 0;
}
m = Math.pow(10, Math.max(c, d));
return(a * m + b * m) / m;
}
//减法
let minus = (a, b) => {
if(!num(a) || !num(b)) {
return null;
}
let c, d, m, n;
try {
c = a.toString().split(".")[1].length;
} catch(e) {
c = 0;
}
try {
d = b.toString().split(".")[1].length;
} catch(e) {
d = 0;
}
m = Math.pow(10, Math.max(c, d));
return(a * m - b * m) / m;
// n = (c >= d) ? c : d;
// return((a * m - b * m) / m).toFixed(n);//数字转换字符串，保留n位小数
}
//乘法
let multiply = (a, b) => {
let m = 0,
c = a.toString(),
d = b.toString();
try {
m += c.split(".")[1].length
} catch(e) {}
try {
m += d.split(".")[1].length
} catch(e) {}
return Number(c.replace(".", "")) * Number(d.replace(".", "")) / Math.pow(10, m)
}
//除法
let division = (a, b) => {
if(!num(a) || !num(b)) {
return null;
}
let c, d, f, g;
try {
c = a.toString().split(".")[1].length;
} catch(e) {
c = 0;
}
try {
d = b.toString().split(".")[1].length;
} catch(e) {
d = 0;
}
with(Math) {
f = Number(a.toString().replace(".", ""));
g = Number(b.toString().replace(".", ""));
return(f / g) * pow(10, d - c);
}
}