js数字千分位

const number = 1234567.89;
const formattedNumber = number.toLocaleString();
console.log(formattedNumber); // 输出: "1,234,567.89"

function addThousandSeparator(num) {
    return num.toString().replace(/\B(?=(\d{3})+(?!\d))/g, ",");
}

const number = 1234567.89;
const formattedNumber = addThousandSeparator(number);
console.log(formattedNumber); // 输出: "1,234,567.89"

const number = 1234567.89;
const formatter = new Intl.NumberFormat('en-US');
const formattedNumber = formatter.format(number);
console.log(formattedNumber); // 输出: "1,234,567.89"

function addThousandSeparator(num) {
    const parts = num.toString().split(".");
    parts[0] = parts[0].replace(/\B(?=(\d{3})+(?!\d))/g, ",");
    return parts.join(".");
}

console.log(addThousandSeparator(-1234567.89)); // 输出: "-1,234,567.89"

function addThousandSeparatorOptimized(num) {
    let str = num.toString();
    let result = '';
    let count = 0;
    for (let i = str.length - 1; i >= 0; i--) {
        result = str[i] + result;
        count++;
        if (count === 3 && i !== 0) {
            result = ',' + result;
            count = 0;
        }
    }
    return result;
}

console.log(addThousandSeparatorOptimized(1234567890)); // 输出: "1,234,567,890"