How to submit a request using JS using POST method (detailed answer combined with code)

function post(URL, PARAMS) {        
    var temp = document.createElement("form");        
    temp.action = URL;        
    temp.method = "post";        
    temp.style.display = "none";        
    for (var x in PARAMS) {        
        var opt = document.createElement("textarea");        
        opt.name = x;        
        opt.value = PARAMS[x];        
        // alert(opt.name)        
        temp.appendChild(opt);        
    }        
    document.body.appendChild(temp);        
    temp.submit();        
    return temp;        
}             
//调用方法 如        
post('pages/statisticsJsp/excel.action', {html :prnhtml,cm1:'sdsddsd',cm2:'haha'});