用js函数加判断做出对象中取整效果

let a = prompt('请输入想要转换的数字');
    let b = prompt('请输入想转换的类型(1:取整 2:向下取整 3: 归零)');
    function c (a,b){
     if( b == 1 ){
       let x = parseFloat(a);
       let g = parseInt(a);
       if( x - g >= 0.5){
         g++;
         console.log(g);
       }else{
         console.log(g);
       }
     } else if( b == 2 ){
       let g = parseInt(a);
       console.log(g);
     }else if( b == 3 ){
       let g = 0 ;
        console.log(g);
     }
    }
    c(a,b);
    // 绝对值
    let a = prompt('请输入');
    if( a >= 0){
      console.log(a);
    }else{
       a = a * -1;
       console.log(a);
    }