Javascript Form Serialize - version 0.2 https://code.google.com/archive/p/form-serialize/downloads

serialize.js

function serialize(form) {
	if (!form || form.nodeName !== "FORM") {
		return;
	}
	var i, j, q = [];
	for (i = form.elements.length - 1; i >= 0; i = i - 1) {
		if (form.elements[i].name === "") {
			continue;
		}
		switch (form.elements[i].nodeName) {
		case 'INPUT':
			switch (form.elements[i].type) {
			case 'text':
			case 'hidden':
			case 'password':
			case 'button':
			case 'reset':
			case 'submit':
				q.push(form.elements[i].name + "=" + encodeURIComponent(form.elements[i].value));
				break;
			case 'checkbox':
			case 'radio':
				if (form.elements[i].checked) {
					q.push(form.elements[i].name + "=" + encodeURIComponent(form.elements[i].value));
				}						
				break;
			case 'file':
				break;
			}
			break;			 
		case 'TEXTAREA':
			q.push(form.elements[i].name + "=" + encodeURIComponent(form.elements[i].value));
			break;
		case 'SELECT':
			switch (form.elements[i].type) {
			case 'select-one':
				q.push(form.elements[i].name + "=" + encodeURIComponent(form.elements[i].value));
				break;
			case 'select-multiple':
				for (j = form.elements[i].options.length - 1; j >= 0; j = j - 1) {
					if (form.elements[i].options[j].selected) {
						q.push(form.elements[i].name + "=" + encodeURIComponent(form.elements[i].options[j].value));
					}
				}
				break;
			}
			break;
		case 'BUTTON':
			switch (form.elements[i].type) {
			case 'reset':
			case 'submit':
			case 'button':
				q.push(form.elements[i].name + "=" + encodeURIComponent(form.elements[i].value));
				break;
			}
			break;
		}
	}
	return q.join("&");
}

serialize.min.js

function serialize(form){if(!form||form.nodeName!=="FORM"){return }var i,j,q=[];for(i=form.elements.length-1;i>=0;i=i-1){if(form.elements[i].name===""){continue}switch(form.elements[i].nodeName){case"INPUT":switch(form.elements[i].type){case"text":case"hidden":case"password":case"button":case"reset":case"submit":q.push(form.elements[i].name+"="+encodeURIComponent(form.elements[i].value));break;case"checkbox":case"radio":if(form.elements[i].checked){q.push(form.elements[i].name+"="+encodeURIComponent(form.elements[i].value))}break;case"file":break}break;case"TEXTAREA":q.push(form.elements[i].name+"="+encodeURIComponent(form.elements[i].value));break;case"SELECT":switch(form.elements[i].type){case"select-one":q.push(form.elements[i].name+"="+encodeURIComponent(form.elements[i].value));break;case"select-multiple":for(j=form.elements[i].options.length-1;j>=0;j=j-1){if(form.elements[i].options[j].selected){q.push(form.elements[i].name+"="+encodeURIComponent(form.elements[i].options[j].value))}}break}break;case"BUTTON":switch(form.elements[i].type){case"reset":case"submit":case"button":q.push(form.elements[i].name+"="+encodeURIComponent(form.elements[i].value));break}break}}return q.join("&")};