What's the way to store result of the for loop as array to localStorage? That is, the result should be: ["./somepage1.html", "./somepage2.html"].
<div class="someclass" href="./somepage1.html">foo</div>
<div class="someclass" href="./somepage2.html">foo</div>
<script>
var foo = document.getElementsByClassName("someclass");
for (var i = 0; i < foo.length; i++)
{
var hrefs = foo[i].getAttribute("href");
console.log(hrefs);
}
</script>
First, create the Array of hrefs.
This uses Array.prototype.map to create a new Array of hrefs from the HTMLCollection of Elements.
var foo = document.getElementsByClassName("someclass");
var arr = Array.prototype.map.call(foo, function(elem) {
return elem.getAttribute("href");
});
Then serialize it using JSON.stringify(), and store it wherever you want in localStorage.
localStorage.foobar = JSON.stringify(arr);
Of course, JSON isn't required to store your data. You can serialize it however you want.
You could have used .join() instead to create a comma-separated string.
var foo = document.getElementsByClassName("someclass");
localStorage.foobar = Array.prototype.map.call(foo, function(elem) {
return elem.getAttribute("href");
}).join(",");
Though this isn't the specific result you described.
Related
I have a single level array of key/value pairs, like this:
var user_filters= ['color=blue', 'size=small', 'shape=circle', 'size=large', 'shape=square']
I need a function to perform the following:
find all duplicate keys
replace the first occurrence of the key/value pair with the second occurrence
delete the second occurrence
In this case, it would produce the following result:
user_filters= ['color=blue', 'size=large', 'shape=square']
Something like...
function update_array(){
$.each(user_filters, function(i){
var key = this.split('=')[0];
if(key is second occurrence in user_filters)
{
var index = index of first occurrence of key
user_filters[index] = user_filters[i];
user_filters.splice(i,1);
}
});
}
What is the best way to do this? Thanks!
I would keep the data in an object and this way any duplicate will automatically overwrite the previous entry..
See this for example:
var user_filters= ['color=blue', 'size=small', 'shape=circle', 'size=large', 'shape=square'];
var object = {};
for (var i = 0; i < user_filters.length; i++) {
var currentItem = user_filters[i].split('=');
var key = currentItem[0];
var value = currentItem[1];
object[key] = value;
}
console.log(object);
You can use a hash object to get the key-value pairs without duplicates and then transform the hash object back into an array like this:
function removeDuplicates(arr) {
var hash = arr.reduce(function(h, e) {
var parts = e.split("=");
h[parts[0]] = parts[1];
return h;
}, {});
return Object.keys(hash).map(function(key) {
return key + "=" + hash[key];
});
}
var user_filters = ['color=blue', 'size=small', 'shape=circle', 'size=large', 'shape=square'];
console.log(removeDuplicates(user_filters));
You could use a Map which does the unique/overriding automatically, and is able to get you an array back in case you need it
var user_filters= ['color=blue', 'size=small', 'shape=circle', 'size=large', 'shape=square'];
var m = new Map(user_filters.map(v => v.split("=")));
console.log([...m.entries()].map(v => v.join("=")));
It would be better to iterate from back of array ,
thus for every unique key you need to keep a variable true or false (initially false).
so if true mean already occurred so deleted it else keep it and make its variable true .
It is much more better approach then your current . you don't have to keep last index and swapping then deleting.
You may convert to json and then back to the array format you want . IN the below code you get the result object in the format you want.
var user_filters= ['color=blue', 'size=small', 'shape=circle', 'size=large', 'shape=square'];
function toJson(obj){
var output = {};
$.each(obj, function(i){
var keyvalPair = this.split('=')
var key = keyvalPair[0];
output[key]= keyvalPair[1];
});
return output;
}
function toArray(obj){
var output = [];
$.each(obj, function(i){
output.push(i+"="+obj[i]);
});
return output;
}
var result = toArray(toJson(user_filters));
console.log(result);
Supposed that I have this JSON STRING that is stored in a vairable:
{"name":"Joene Floresca"},{"name":"Argel "}
How can I make it
["Joene", "Argel"]
You mention you have a string. Use JSON.parse for that. Also, make sure it is an array. Afterwards, you can manually iterate through each object in the array and push the value
var str = '[{"name": "Joene Floresca"},{ "name": "Argel "}]';
var objA = JSON.parse(str);
var values = [];
for (var i = 0; i < objA.length; i++) {
for (var key in objA[i]) {
values.push(objA[i][key]);
}
}
console.log(values);
Assuming your JSON is an array, you can use map:
// Your JSON string variable
var jsonString = '[{"name":"Joene Floresca"},{"name":"Argel "}]';
// Parse the JSON to a JS Object
var jsObject = $.parseJSON(jsonString);
// Use map to iterate the array
var arr = $.map(jsObject, function(element) {
// Return the name element from each object
return element.name;
});
console.log(arr); // Prints ["Joene Floresca", "Argel "]
<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
You can iterate over objects inside array and store the names in a second array.
var data = JSON.parse('[{"name":"Joene Floresca"},{"name":"Argel "}]');
var names = [];
data.forEach(function(model) {
names.push(model.name);
});
// names now contains ["Joene Floresca", "Argel"]
alert(names);
I have an array called values which has this data
var values=new Array();
values.push("english":"http://www.test.in/audio_ivrs/sr_listenglishMSTR001.wav");
values.push("kannada":"http://www.test.in/audio_ivrs/sr_listfrenchMSTR001.wav");
When I do JSON.stringify(values) I get values with square brackets, but I need a JSON string a shown below with urllist appended at the first.
{
"urlList":{
"english":"http://www.test.in/audio_ivrs/sr_listenglishMSTR001.wav",
"kannada":"http://www.test.in/audio_ivrs/sr_listfrenchMSTR001.wav"
}
}
Your code as you've defined it will give you errors. This is not valid JavaScript; you can't create an array element like this.
values.push("english":"http://www.test.in/audio_ivrs/sr_listenglishMSTR001.wav");
If you want the structure you've specified in your question then you'll need to use a nested object rather than an array to contain the key/value pairs.
var values = {
urlList: {}
};
values.urllist.english = "http://www.test.in/audio_ivrs/sr_listenglishMSTR001.wav";
values.urllist.kannada = "http://www.test.in/audio_ivrs/sr_listfrenchMSTR001.wav";
DEMO
HOWEVER...
Let's assume for a moment that what you meant to code was this (note the curly braces):
var values=new Array();
values.push({"english":"http://www.test.in/audio_ivrs/sr_listenglishMSTR001.wav"});
values.push({"kannada":"http://www.test.in/audio_ivrs/sr_listfrenchMSTR001.wav"});
This would tell me that you're pushing objects into an array which is perfectly valid JavaScript.
To get this information from the array into the structure you need you can use something like this loop:
var out = {
urlList: {}
};
for (var i = 0, l = values.length; i < l; i++) {
var el = values[i];
var key = Object.keys(el);
var value = el[key];
out.urlList[key] = value;
}
JSON.stringify(out);
DEMO
With this code,
h = {}
for (var i in [0,1]){ h[i.ToString] = i; }
I expected same result with h["1"] = 1 and h["2"] = 2.
Why is this code doesn't work, and how can I define hash key dynamically in javascript?
The for .. in loop in JS iterates over keys, not over values (https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Statements/for...in).
So in your case, you iterate over the keys of the array you have in there.
Those will be 0, 1, 2 ... no matter what you put in there.
What you could do instead would be something like this:
var obj = {};
var data = [1,2,3,4];
data.forEach(function(val) {
obj[val] = val;
});
Solving another array manipulation, and I'm taking longer than usual to solve this. I need help in combining array values:
var array1 = ["alpha|LJ", "bravo|MH", "charlie|MH", "delta|MF",
"echo|16", "{foxtrot}|GG", "{golf}|HS"];
var array2 = ["charlie-{golf}-{foxtrot}", "echo-{golf}"]; //some templates
such that the final array be:
final_array = ["alpha-LJ", "bravo-MH", "charlie-HS-GG-MH", "delta-MF",
"echo-HS-16"];
To make it clear how I arrived with the final_array, alpha, bravo and delta only got their "|" replaced with "-" since they are not found on my array2 template. charlie and echo got the template so the respective values of the {} were replaced based on array1. Array1 honestly is not the best key:value relationship that I could come up for now.
Here are some requirementL:
* Anything in array1 with {} braces are not meant to be templated.
* Keywords in array2 will always have a matching value in array1.
I've read about jquery .map() and thinking that it is achievable using this, maybe together with Regexp. Hope you'll utilize these. Also, if it helps, final_array can be of any order.
I really need to up my knowledge on these two topics... :|
Thank you in advance.
Edit: Updated to match your output and comment some of the madness. This doesn't feel like it's the most efficient, given the split() done to values at the start and then again at the end...but it works.
function funkyTransform( values, templates ){
// Make a copy of the array we were given so we can mutate it
// without rudely changing something passed to our function.
var result = values.concat();
// Map {value} entries for later lookup, and throw them out of the result
var valueMap = {};
for (var i=result.length-1;i>=0;--i){
var pair = result[i].split('|');
if (pair[0][0]=="{"){
valueMap[pair[0]] = pair[1];
result.splice(i,1); // Yank this from the result
}
}
console.log(valueMap);
// {
// "{foxtrot}": "GG",
// "{golf}": "HS"
// }
// Use the value map to replace text in our "templates", and
// create a map from the first part of the template to the rest.
// THIS SHOULD REALLY SCAN THE TEMPLATE FOR "{...}" PIECES
// AND LOOK THEM UP IN THE MAP; OOPS O(N^2)
var templateMap = {};
for (var i=templates.length-1;i>=0;--i){
var template = templates[i];
for (var name in valueMap){
if (valueMap.hasOwnProperty(name)){
template = template.replace(name,valueMap[name]);
}
}
var templateName = template.split('-')[0];
templateMap[ templateName ] = template.slice(templateName.length+1);
}
console.log(templateMap);
// {
// "charlie": "HS-GG",
// "echo": "HS"
// }
// Go through the results again, replacing template text from the templateMap
for (var i=result.length-1;i>=0;--i){
var pieces = result[i].split('|');
var template = templateMap[pieces[0]];
if (template) pieces.splice(1,0,template);
result[i] = pieces.join('-');
}
return result;
}
var output = funkyTransform( array1, array2 );
console.log(output);
// ["alpha-LJ", "bravo-MH", "charlie-HS-GG-MH", "delta-MF", "echo-HS-16"]
This managed to get your desired output, though I made a few assumptions:
Anything in array1 with {} braces are not meant to be templated.
Keywords in array2 will always have a matching value in array1 (this can easily be changed, but not sure what your rule would be).
Code:
// This is the main code
var final_array = $.map(array1, function (item) {
var components = item.split('|');
// Ignore elements between {} braces
if (/^\{.*\}$/.test(components[0])) return;
components[0] = template(components[0]);
return components.join('-');
});
// Helper to lookup array2 for a particular string and template it
// with the values from array1
function template(str) {
var index = indexOfMatching(array2, str, '-');
if (index == -1) return str;
var components = array2[index].split('-');
var result = [str];
for (var i = 1; i < components.length; i++) {
result.push(array1[indexOfMatching(array1, components[i], '|')]
.split('|')[1]);
}
return result.join('-');
}
// Helper to for looking up array1 and array2
function indexOfMatching(array, target, separator) {
for (var i = 0; i < array.length; i++) {
if (array[i].split(separator)[0] === target) return i;
}
return -1;
}