问题
I'm loading options into an HTML5 datalist element dynamically. However, the browser attempts to show the datalist before the options have loaded. This results in the list not being shown or sometimes a partial list being shown. Is there any way to refresh the list via JavaScript once the options have loaded?
HTML
<input type="text" id="ingredient" list="ingredients">
<datalist id="ingredients"></datalist>
JavaScript
$("#ingredient").on("keyup", function(event) {
var value = $(this).val();
$.ajax({
url: "/api/ingredients",
data: {search: value.length > 0 ? value + "*" : ""},
success: function(ingredients) {
$("#ingredients").empty();
for (var i in ingredients) {
$("<option/>").html(ingredients[i].name).appendTo("#ingredients");
}
// Trigger a refresh of the rendered datalist
}
});
});
Note: In Chrome and Opera, the entire list is only shown if the user clicks on the input after entering text. However, I'd like the entire list to appear as the user types. Firefox is not a problem, as it appears to refresh the list automatically when the options are updated.
UPDATE
I'm not sure this question has a satisfactory answer, as I believe this is simply a shortcoming of certain browsers. If a datalist is updated, the browser should refresh the list, but some browsers (including Chrome and Opera) simply do not do this. Hacks?
回答1:
Quite a long time after question but I found a workaround for IE and Chrome (not tested on Opera and already OK for Firefox).
The solution is to focus the input at the end of success (or done) function like this :
$("#ingredient").on("keyup", function(event) {
var _this = $(this);
var value = _this.val();
$.ajax({
url: "/api/ingredients",
data: { search: value.length > 0 ? value + "*" : "" },
success: function(ingredients) {
$("#ingredients").empty();
for (var i in ingredients) {
$("<option/>").html(ingredients[i].name).appendTo("#ingredients");
}
// Trigger a refresh of the rendered datalist
// Workaround using focus()
_this.focus();
}
});
It works on Firefox, Chrome and IE 11+ (perhaps 10).
回答2:
You can probably eliminate the problem if you don't make AJAX request on every key stroke. You can try throttle technique using set/cleatTimeout to issue request after 500ms after the last char typed:
$("#ingredient").on("keyup", function(event) {
clearTimeout($(this).data('timeout'));
$(this).data('timeout', setTimeout($.proxy(function() {
var value = $(this).val();
$.ajax({
url: "/api/ingredients",
data: {search: value.length > 0 ? value + "*" : ""},
success: function(ingredients) {
$("#ingredients").empty();
for (var i = 0; i < ingredients.length; i++) {
$("<option/>").html(ingredients[i].name).appendTo("#ingredients");
}
}
});
}, this), 500));
});
回答3:
Yoyo gave the correct solution, but here's a better way to structure your inserts into the DOM.
$("#ingredient").on("keyup", function(event) {
var _this = $(this);
var value = _this.val();
$.ajax({
url: "/api/ingredients",
data: { search: value.length > 0 ? value + "*" : "" },
success: function(ingredients) {
var options = ingredients.map(function(ingredient) {
var option = document.createElement('option');
option.value = ingredient.name;
return option;
});
$("#ingredients")
.empty()
.append(options);
// Trigger a refresh of the rendered datalist
// Workaround using focus()
_this.focus();
}
});
Less DOM manipulation
With this refinement, I'm only inserting into the DOM a single time per each successful callback. This cuts down on the browser needing to re-render, and will help improve any "blips" in the view.
Functional Programming and Less Idiomatic jQuery
Here we are using the Array.prototype.map to clean up some of the jQuery and make things a bit less idiomatic. You can see from the ECMA Chart that this function will work in all browsers you are targeting.
Not Hacky
This by no means is hacky. IE appears to be the only browser that doesn't automatically refresh the input to display the new list options. focus() is just a way to ensure the input is refocused which forces a refresh of the view.
This solution works very well in all of the browsers that my company has to support internally, IE10+ Chrome and Firefox.
回答4:
Place your #ingredients element is inside #container and try this code:
$.ajax({
url: "/api/ingredients",
data: {search: value.length > 0 ? value + "*" : ""},
success: function(ingredients) {
$("#ingredients").remove();
var item = $('<datalist id="ingredients"></datalist>');
for (var i in ingredients) {
item.append("<option>"+ ingredients[i].name +"</option>");
}
item.appendTo('#container');
}
});
even better without #container and using jQuery replaceWith():
$.ajax({
url: "/api/ingredients",
data: {search: value.length > 0 ? value + "*" : ""},
success: function(ingredients) {
var item = $('<datalist id="ingredients"></datalist>');
for (var i in ingredients) {
item.append("<option>"+ ingredients[i].name +"</option>");
}
$("#ingredients").replaceWith(item);
}
});
回答5:
Your issue is that the AJAX is asynchronous.
You'd actually have to have a callback for the AJAX which you call onSuccess which would then update the datalist. Of course, then you might not have great performance/still have a "skipping" behavior, where your datalist options are lagging behind.
If your list of items from the AJAX isn't too large, you should:
1. load the ENTIRE list into memory array with the first query, then...
1. use a filtering function that is applied to the array each time you have a keyUp event.
回答6:
I had the same problem when updating datalist.
The new values would not show until new input event.
I tried every suggested solutions but nothing using Firefox and updating datalist via AJAX.
However, I solved the problem (for simplicity, I'll use your example):
<input type="text" id="ingredient" list="ingredients" **autocomplete="off"**>
<datalist id="ingredients"></datalist>
$("#ingredient").on("**input**", function(event) { ....}
Autocomplete and input is the couple that solve my problems and it works with Chrome too.
来源：https://stackoverflow.com/questions/26610752/how-do-you-refresh-an-html5-datalist-using-javascript