问题
Finally, I managed to do this:
function validar(dato_a_validar, url, secc)
{
var datastr = "secc=" + secc + "&dato=" + dato_a_validar;
return new Promise(function(resolve, reject) {
$.ajax({
type:'GET',
url:url,
data:datastr,
success:function(response) { resolve(response); },
error:function(response) { reject(response); }
});
});
}
async function check_submit()
{
init(); // sets some global variables
errores_personal_cnt = 0; // error counter
var dni_ctl = document.getElementById("frm_funcionario_dni");
var dni = dni_ctl.value;
dni_ctl.style.borderColor = "black";
dni_ctl.style.backgroundColor = "none";
const estado = await validar(dni, url_validacion, "dni")
.then(salida => estadoValidacion(dni_ctl, salida)) // estadoValidacion() sets some colour and form control title
.catch(error => estadoValidacion(dni_ctl, "error"));
$.when(estado).done(console.log("Errores: " + errores_personal_cnt));
return false; // this is set for tests purposes, but is always ignored.
}
On the onsubmit
event, async function check_submit()
is called. validar(...)
function returns a promise
(I guess), and with .then()
and .catch()
y handle both results. However, even when there are wrong fields, the form is submitted.
I think the reason the form is always submitted is because I have some wrong code somewhere but I can't figure out where.
Thanks!
回答1:
Explaining with an example suppose I have a form that I validate using promised based approach. Suppose validar()
is a function that does some validation and takes 3 secs (I have many fields you know!). But when used like this it fails! see in below comments as to why is so.
<form action="google.com" id="frm">
<input id="txt">
<button type="submit">submit</button>
</form>
<script>
document.getElementById('frm').onsubmit = () => {
var check = check_submit();
console.log(check); //Promise {<pending>}
console.log(check ? true : false) // which is evaluates to true! (check ? true : false) <-- true
//So browser proceeds with form's default behavior which is to submit on google.com
}
function validar() {
return new Promise(function(resolve, reject) {
setTimeout(() => resolve(false), 3000)
});
}
async function check_submit() {
var result = validar(); // <-- this line NEVER WAITS for the promise of validar to get resolve() 'ed
// instead its current value which is Promise {<pending>} is used immediatly and RETURNED!
return result;
}
</script>
How to make it work then?
It's simple just stop the default behavior by returning false in onsubmit
unconditionally and manually submit form(if valid) when the promise value gets resolved
<form action="google.com" id="frm">
<input id="txt">
<button type="submit">submit</button>
</form>
<script>
document.getElementById('frm').onsubmit = () => {
check_submit(); //<-- will handle our form submission business
return false; //unconditional
}
function validar() {
return new Promise(function(resolve, reject) {
setTimeout(() => resolve(false), 3000)
});
}
async function check_submit() {
var result = await validar(); //<-- this line NOW WAITS (due to await) for the promise of validar to get resolve() 'ed
if (result) {
alert('submitting form as validar returned true')
document.getElementById('frm').submit(); // submit manully as promise'd value returned true
} else
alert('meh')
}
</script>
来源:https://stackoverflow.com/questions/61983720/js-ajax-promise-dependant-submit-always-submitted