My guess is: If it is used for page display, then strings don’t matter, right? If it is used for operation, it doesn't matter even if it is 1 (not 1.00), right?

1.00 This format can only be saved as a string, and cannot be saved as a numeric type.

No matter what you do, if you want to display something like 1.00, you can only use strings.

First of all, the toFixed method itself is buggy. Secondly, the Number structure in js does not contain precision. If you need numbers that contain precision, you can just write a class yourself

var num=1.256;
Math.floor(Math.round(num*100))/100;

可以封装成方法：
function unitNormalization(arr,digit){
        /*单位规整*/
        var digit=digit||0;
        var prence=Math.pow(10,digit);
        if(Array.isArray(arr)){
            var backArr=[];
            for(var i=0;i<arr.length;i++){
                backArr.push(Math.rou(Math.round(arr[i]*prence))/prence);
            }
            return backArr;
        }else{
            var num=Math.floor(Math.round(arr*prence))/prence;
            return num
        }
    }

unitNormalization(1.253,2)//1.25
unitNormalization(1.257,2)//1.26

parseFloat(1.236.toFixed(2))