js取小数点后两位（四舍五入、直接截取）

// 1.toFixed方法。————》四舍五入
	let num = 46.123456;
    let numTo = num.toFixed(2)
	console.log(numTo) // 46.12
	
	let num2 = 46.12743;
	let numTo2 = num2.toFixed(2)
	console.log(numTo2) // 46.13

// 2.通过substring截取。————》直接截取
    let num = 46.123456;
    let s = num.toString();
    let result = s.substring(0,s.indexOf(".")+3); //截取小数点后2位
    let result2 = s.substring(0,s.indexOf(".")+5); //截取小数点后4位
    console.log(result);  // 46.12
    console.log(result2); // 46.1234

 
// 3. 正则表达式。————》直接截取
    let num = 22.123456;
    let re = /([0-9]+\.[0-9]{
    
    2})[0-9]*/;
    let aNew = num.toString().replace(re,"$1");
    console.log(aNew);// 22.12

 
// 4.数据类型保留上。————》四舍五入
    let num=22.123456;
    console.log( Math.round(num*10000)/10000); // 22.1235
    console.log( Math.round(num*1000)/1000); // 22.123
    console.log( Math.round(num*100)/100); // 22.12
    console.log( Math.round(num*10)/10);// 22.1