Js数字三位一逗号间隔的方法

1.

parseFloat(number).toLocaleString();

示例：
var number = "12345678.000";
console.log(parseFloat(number).toLocaleString()); //输出12,345,678.000 

2.

function formatNumber(str){
        str += '';  
        var x = str.split('.');  
        var x1 = x[0];  
        var x2 = x.length > 1 ? '.' + x[1] : '';  
        var rgx = /(\d+)(\d{3})/;  
        while (rgx.test(x1)) {  
            x1 = x1.replace(rgx, '$1' + ',' + '$2');  
        }  
        return x1 + x2;  
    };
console.log(formatNumber("12345678.000")) //输出12,345,678.000