问题
Just wondering if there is anything built-in to Javascript that can take a Form and return the query parameters, eg: "var1=value&var2=value2&arr[]=foo&arr[]=bar..."
I've been wondering this for years.
回答1:
I tried to search for an answer to this question some while ago, but I ended up writing my own function that extracts the values from the form ..
it's not perfect but it fits my needs.
function form_params( form )
{
var params = new Array()
var length = form.elements.length
for( var i = 0; i < length; i++ )
{
element = form.elements[i]
if(element.tagName == 'TEXTAREA' )
{
params[element.name] = element.value
}
else if( element.tagName == 'INPUT' )
{
if( element.type == 'text' || element.type == 'hidden' || element.type == 'password')
{
params[element.name] = element.value
}
else if( element.type == 'radio' && element.checked )
{
if( !element.value )
params[element.name] = "on"
else
params[element.name] = element.value
}
else if( element.type == 'checkbox' && element.checked )
{
if( !element.value )
params[element.name] = "on"
else
params[element.name] = element.value
}
}
}
return params;
}
form_params returns a (key -> value) mapping of the parameters. the input is the form element (DOM Element)
It doesn't handle fields that allow multiple selection.
回答2:
2k19 update: use Josh's solution with URLSearchParams.toString().
Old answer:
Without jQuery
var params = {
parameter1: 'value_1',
parameter2: 'value 2',
parameter3: 'value&3'
};
var esc = encodeURIComponent;
var query = Object.keys(params)
.map(k => esc(k) + '=' + esc(params[k]))
.join('&');
For browsers that don't support arrow function syntax which requires ES5, change the .map... line to
.map(function(k) {return esc(k) + '=' + esc(params[k]);})
回答3:
If you're using jQuery you might want to check out jQuery.param() http://api.jquery.com/jQuery.param/
Example:
var params = {
parameter1: 'value1',
parameter2: 'value2',
parameter3: 'value3'
};
var query = $.param(params);
document.write(query);
回答4:
This doesn't directly answer your question, but here's a generic function which will create a URL that contains query string parameters. The parameters (names and values) are safely escaped for inclusion in a URL.
function buildUrl(url, parameters){
var qs = "";
for(var key in parameters) {
var value = parameters[key];
qs += encodeURIComponent(key) + "=" + encodeURIComponent(value) + "&";
}
if (qs.length > 0){
qs = qs.substring(0, qs.length-1); //chop off last "&"
url = url + "?" + qs;
}
return url;
}
// example:
var url = "http://example.com/";
var parameters = {
name: "George Washington",
dob: "17320222"
};
console.log(buildUrl(url, parameters));
// => http://www.example.com/?name=George%20Washington&dob=17320222
回答5:
The URLSearchParams API is available in all modern browsers. For example:
const params = new URLSearchParams({
var1: "value",
var2: "value2",
arr: "foo",
});
console.log(params.toString());回答6:
With jQuery you can do this by $.param
$.param({ action: 'ship', order_id: 123, fees: ['f1', 'f2'], 'label': 'a demo' })
// -> "action=ship&order_id=123&fees%5B%5D=f1&fees%5B%5D=f2&label=a+demo"
回答7:
ES2017 (ES8)
Making use of Object.entries(), which returns an array of object's [key, value] pairs. For example, for {a: 1, b: 2} it would return [['a', 1], ['b', 2]]. It is not supported (and won't be) only by IE.
Code:
const buildURLQuery = obj =>
Object.entries(obj)
.map(pair => pair.map(encodeURIComponent).join('='))
.join('&');
Example:
buildURLQuery({name: 'John', gender: 'male'});
Result:
"name=John&gender=male"
回答8:
No, I don't think standard JavaScript has that built in, but Prototype JS has that function (surely most other JS frameworks have too, but I don't know them), they call it serialize.
I can reccomend Prototype JS, it works quite okay. The only drawback I've really noticed it it's size (a few hundred kb) and scope (lots of code for ajax, dom, etc.). Thus if you only want a form serializer it's overkill, and strictly speaking if you only want it's Ajax functionality (wich is mainly what I used it for) it's overkill. Unless you're careful you may find that it does a little too much "magic" (like extending every dom element it touches with Prototype JS functions just to find elements) making it slow on extreme cases.
回答9:
querystring can help.
So, you can
const querystring = require('querystring')
url += '?' + querystring.stringify(parameters)
回答10:
If you don't want to use a library, this should cover most/all of the same form element types.
function serialize(form) {
if (!form || !form.elements) return;
var serial = [], i, j, first;
var add = function (name, value) {
serial.push(encodeURIComponent(name) + '=' + encodeURIComponent(value));
}
var elems = form.elements;
for (i = 0; i < elems.length; i += 1, first = false) {
if (elems[i].name.length > 0) { /* don't include unnamed elements */
switch (elems[i].type) {
case 'select-one': first = true;
case 'select-multiple':
for (j = 0; j < elems[i].options.length; j += 1)
if (elems[i].options[j].selected) {
add(elems[i].name, elems[i].options[j].value);
if (first) break; /* stop searching for select-one */
}
break;
case 'checkbox':
case 'radio': if (!elems[i].checked) break; /* else continue */
default: add(elems[i].name, elems[i].value); break;
}
}
}
return serial.join('&');
}
回答11:
You don't actually need a form to do this with Prototype. Just use Object.toQueryString function:
Object.toQueryString({ action: 'ship', order_id: 123, fees: ['f1', 'f2'], 'label': 'a demo' })
// -> 'action=ship&order_id=123&fees=f1&fees=f2&label=a%20demo'
回答12:
I'm not entirely certain myself, I recall seeing jQuery did it to an extent, but it doesn't handle hierarchical records at all, let alone in a php friendly way.
One thing I do know for certain, is when building URLs and sticking the product into the dom, don't just use string-glue to do it, or you'll be opening yourself to a handy page breaker.
For instance, certain advertising software in-lines the version string from whatever runs your flash. This is fine when its adobes generic simple string, but however, that's very naive, and blows up in an embarrasing mess for people whom have installed Gnash, as gnash'es version string happens to contain a full blown GPL copyright licences, complete with URLs and <a href> tags. Using this in your string-glue advertiser generator, results in the page blowing open and having imbalanced HTML turning up in the dom.
The moral of the story:
var foo = document.createElement("elementnamehere");
foo.attribute = allUserSpecifiedDataConsideredDangerousHere;
somenode.appendChild(foo);
Not:
document.write("<elementnamehere attribute=\""
+ ilovebrokenwebsites
+ "\">"
+ stringdata
+ "</elementnamehere>");
Google need to learn this trick. I tried to report the problem, they appear not to care.
回答13:
As Stein says, you can use the prototype javascript library from http://www.prototypejs.org.
Include the JS and it is very simple then, $('formName').serialize() will return what you want!
回答14:
For those of us who prefer jQuery, you would use the form plugin: http://plugins.jquery.com/project/form, which contains a formSerialize method.
回答15:
You can do that nowadays with FormData and URLSearchParams without the need to loop over anything.
const formData = new FormData(form);
const searchParams = new URLSearchParams(formData);
const queryString = searchParams.toString();
Older browsers will need a polyfill, though.
回答16:
These answers are very helpful, but i want to add another answer, that may help you build full URL.
This can help you concat base url, path, hash and parameters.
var url = buildUrl('http://mywebsite.com', {
path: 'about',
hash: 'contact',
queryParams: {
'var1': 'value',
'var2': 'value2',
'arr[]' : 'foo'
}
});
console.log(url);
You can download via npm https://www.npmjs.com/package/build-url
Demo:
;(function () {
'use strict';
var root = this;
var previousBuildUrl = root.buildUrl;
var buildUrl = function (url, options) {
var queryString = [];
var key;
var builtUrl;
var caseChange;
// 'lowerCase' parameter default = false,
if (options && options.lowerCase) {
caseChange = !!options.lowerCase;
} else {
caseChange = false;
}
if (url === null) {
builtUrl = '';
} else if (typeof(url) === 'object') {
builtUrl = '';
options = url;
} else {
builtUrl = url;
}
if(builtUrl && builtUrl[builtUrl.length - 1] === '/') {
builtUrl = builtUrl.slice(0, -1);
}
if (options) {
if (options.path) {
var localVar = String(options.path).trim();
if (caseChange) {
localVar = localVar.toLowerCase();
}
if (localVar.indexOf('/') === 0) {
builtUrl += localVar;
} else {
builtUrl += '/' + localVar;
}
}
if (options.queryParams) {
for (key in options.queryParams) {
if (options.queryParams.hasOwnProperty(key) && options.queryParams[key] !== void 0) {
var encodedParam;
if (options.disableCSV && Array.isArray(options.queryParams[key]) && options.queryParams[key].length) {
for(var i = 0; i < options.queryParams[key].length; i++) {
encodedParam = encodeURIComponent(String(options.queryParams[key][i]).trim());
queryString.push(key + '=' + encodedParam);
}
} else {
if (caseChange) {
encodedParam = encodeURIComponent(String(options.queryParams[key]).trim().toLowerCase());
}
else {
encodedParam = encodeURIComponent(String(options.queryParams[key]).trim());
}
queryString.push(key + '=' + encodedParam);
}
}
}
builtUrl += '?' + queryString.join('&');
}
if (options.hash) {
if(caseChange)
builtUrl += '#' + String(options.hash).trim().toLowerCase();
else
builtUrl += '#' + String(options.hash).trim();
}
}
return builtUrl;
};
buildUrl.noConflict = function () {
root.buildUrl = previousBuildUrl;
return buildUrl;
};
if (typeof(exports) !== 'undefined') {
if (typeof(module) !== 'undefined' && module.exports) {
exports = module.exports = buildUrl;
}
exports.buildUrl = buildUrl;
} else {
root.buildUrl = buildUrl;
}
}).call(this);
var url = buildUrl('http://mywebsite.com', {
path: 'about',
hash: 'contact',
queryParams: {
'var1': 'value',
'var2': 'value2',
'arr[]' : 'foo'
}
});
console.log(url);回答17:
Is is probably too late to answer your question.
I had the same question and I didn't like to keep appending strings to create a URL. So, I started using $.param as techhouse explained.
I also found a URI.js library that creates the URLs easily for you. There are several examples that will help you: URI.js Documentation.
Here is one of them:
var uri = new URI("?hello=world");
uri.setSearch("hello", "mars"); // returns the URI instance for chaining
// uri == "?hello=mars"
uri.setSearch({ foo: "bar", goodbye : ["world", "mars"] });
// uri == "?hello=mars&foo=bar&goodbye=world&goodbye=mars"
uri.setSearch("goodbye", "sun");
// uri == "?hello=mars&foo=bar&goodbye=sun"
// CAUTION: beware of arrays, the following are not quite the same
// If you're dealing with PHP, you probably want the latter…
uri.setSearch("foo", ["bar", "baz"]);
uri.setSearch("foo[]", ["bar", "baz"]);`
回答18:
var params = { width:1680, height:1050 };
var str = jQuery.param( params );
console.log(str)<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.1/jquery.min.js"></script>来源：https://stackoverflow.com/questions/316781/how-to-build-query-string-with-javascript