A JavaScript instance for detecting form data

This article mainly introduces a JavaScript instance for detecting form data. It is very simple and practical. It is suitable for beginners to use a JavaScript instance for detecting form data. It is very simple and practical. If you are interested, you can check it out.

   
  One JavaScript instance per day-Detects form data Script window. onload = function () {document. getElementById ("thirdfield "). onchange = validateField; document. getElementById ("firstfield "). onblur = mandatoryField; document. getElementById ("testform "). onsubmit = finalCheck;} function validateField () {removeAlert (); if (! IsNaN (parseFloat (this. value) {resetField (this);} else {badField (this); generateAlert ("You entered an invalid value in Third Field. only numeric values such as 105 or 3.45 are allowed ");} function removeAlert () {var msg = document. getElementById ("msg"); if (msg) {document. body. removeChild (msg) ;}} function resetField (elem) {elem. parentNode. setAttribute ("style", "background-color: # fff"); var vali D = elem. getAttribute ("aria-invalid"); if (valid) elem. removeAttribute ("aria-invalid");} function badField (elem) {elem. parentNode. setAttribute ("style", "background-color # background"); elem. setAttribute ("aria-invalid", "true");} function generateAlert (txt) {var txtNd = document. createTextNode (txt); msg = document. createElement ("p"); msg. setAttribute ("role", "alert"); msg. setAttribute ("id", "msg"); msg. setAtt Rigoal ("class", "alert"); msg. appendChild (txtNd); document. body. appendChild (msg);} function mandatoryField () {removeAlert (); if (this. value. length> 0) {resetField (this) ;}else {badField (this); generateAlert ("You must enter a value into First Field") ;}} function finalCheck () {// console. log ("aaa"); removeAlert (); var fields = document. querySelectorAll ('input [aria-invalid = "true"] '); // var fields = d Ocument. querySelectorAll ("input [aria-invalid = 'true']"); // Error !!! Console. log (fields); if (fields. length> 0) {generateAlert ("You have incorrect fields entries that must be fixed before you can submit this form"); return false;} script        

For more articles about JavaScript instances used to detect form data, refer to PHP!