JS中的数学计算<之简单实例讲解>

1.取余数   %

var a=10%3; //a=1

 

2.取绝对值  Math.abs()

var a=Math.abs(-102.1); var b=Math.abs(102.1); //a=102.1;b=102.1

 

3.截取小数点后长度并进行四舍五入 toFixed()

var num_1 = new Number(13.53); alert(num_1.toFixed(1)); alert(num_1.toFixed(0)); //13.5 //14

var num_2 = new Number(13.56); alert(num_2.toFixed(1)); alert(num_2.toFixed(0)); //13.6 //14

 

4.取最小值 Math.min()

Math.min(5,7) Math.min(-3,5) Math.min(-3,-5) (Math.min(7.25,7.30) //结果 //5 //-3 //-5 //7.25

 

5.取最大值  Math.max()

Math.max(5,7,9) Math.max(-3,5) Math.max(-3,-5) Math.max(7.25,7.30) //结果 //9 //5 //-3 //7.30

 

6.指数计数法 和 截取数字固定长度 toPrecision()

var a=1000.25; alert(a.toPrecision(1)) alert(a.toPrecision(2)) alert(a.toPrecision(4)) alert(a.toPrecision(6)) alert(a.toPrecision(8)) //结果 //1e+3 //1.0e+3 //1000 //1000.25 //1000.2500

 

7.把一个数字舍入为最接近的整数 round()

Math.round(0.60) Math.round(0.50) Math.round(0.49) Math.round(-4.40) Math.round(-4.60) //结果 //1 //1 //0 //-4 //-5