how to add more values to variable string - javascript

i have this variable below,
var arr = {
lines: 1,
angle: 2
};
how would i append / push this into my arr variable?
var arr2 = { hi : 3 }
I've tried push() and just simply adding the two. but failed
var r = arr+''+arr2;
alert(r.toSource());
the alert gives me this
(new String("[object Object][object Object]"))

you can add a new property in a static way, like this:
arr.hi = 3;
but if you want to add all the properties from another object (a merge of object's properties) here a simple snippet:
var arr = {
lines: 1,
angle: 2
};
alert(JSON.stringify(arr));
var arr2 = {
hi : 3,
jsIs: "aWeSoMe"
};
//add all the key/value pairs of arr2 to arr
Object.keys(arr2).forEach(function (key) {
arr[key] = arr2[key];
});
alert(JSON.stringify(arr));

You can assign that into arr variable using
// if you want to enter object itself
arr.arr2 = arr2;
// if you want to remove arr2
delete arr2
// if you want to include just hi
arr.hi = arr2.hi;
// if you want to remove hi from arr2
delete arr2.hi

Related

Filter if array include an element of another array

I have two arrays like:
arr1 = ["orange","banana"]
arr2 = [{"fruit"= ["pineapple","banana"]},{"fruit"= ["grapes","apple"]},{"fruit"= ["apple","orange"]}]
And i need to filter if in second array exists an item of the first.
I am trying to do this:
let kFilter = arr1.map(itemY => { return itemY; });
let filteredK = arr2.filter(itemX => kFilter.includes(itemX.fruit));
But no success :-(
First to avoid too much iteration convert the simple array to an object something like following. Otherwise the complexity will be high
const fruitMap = {
"orange": 1,
"banana": 1
};
Then you have to iterate over each of the items in second array
arr2.forEach(fruitsObj => {
let arr = fruitsObj['fruit'];
for (let i = 0; i < arr.length(); i ++) {
if (fruitMap[arr[i]]) {
arr.splice(i, 1);
}
}
})
//declaration variables correctly
let arr1 = ["orange","banana"]
let arr2 = [{"fruit" : ["pineapple","banana"]},{"fruit" : ["grapes","apple"]},{"fruit": ["apple","orange"]}];
//filter using reduce
arr2.filter((e)=>arr1.reduce((a,i)=>a||e["fruit"].includes(i),false))
//filter using some
arr2.filter((e)=>arr1.some((i)=>e["fruit"].includes(i)))

Javascript two array merge( key and value)

I have two array. I want to merge this two arrays into one array. One array consisting keys and another one values.My array looks like
productId = [8,7,9];//Key Element
quantity = ["5","1","3"];//Value Element
//expected new array
newarray = {
"8": 5,
"7": 1,
"9": 3
}
I already tried to merge these arrays, in this way
var newArray = {};
for(var i=0; i< productId.length; i++){
newArray[productId[i]] = quantity [i];
}
console.log(newArray);
It returns
Object [ <7 empty slots>, "5", "1", "3" ]
You are working in firefox so you may get this type of issue because the problem might be caused at how Firefox' console.log has interpreted the input object.
Please look here
Empty slots in JavaScript objects?
Try this
var productId = [8,7,9];
var quantity = ["5","1","3"];
var newarray = {};
productId.forEach((key, i) => newarray[key] = quantity[i]);
console.log(newarray);
Try the following:
var productId = [8,7,9];//Key Element
var quantity = ["5","1","3"];//Value Element
var obj = {};
var i = 0;
for(var k of productId) {
obj[k] = parseInt(quantity[i]);
i++;
}
console.log(obj);
Your new "array" is not an Array but an Object.
You can iterate on one of the arrays using Array.reduce to construct the object.
Something like that:
const arr1 = ['8', '2', '4'];
const arr2 = ['28', '12', '45'];
const result = arr1.reduce((obj, currentItem, index) => {
obj[currentItem] = arr2[index];
return obj;
}, {});
console.log(result);

Javascript extend Array so it duplicates and reverses

If I have an array like [1,2,3,4], and I want to duplicate and reverse it, how do I get it to return [1,2,3,4,4,3,2,1]?
Array.prototype.duplicateAndReverse = function() {
const initial = this;
const reversed = initial.reverse();
return initial.concat(reversed);
}
What am i doing wrong here? It returns [4,3,2,1,4,3,2,1]
Try this:
Array.prototype.duplicateAndReverse = function() {
const initial = this;
const reversed = initial.slice().reverse();
return initial.concat(reversed);
}
var myArray = [1,2,3,4];
alert(myArray.duplicateAndReverse());
Your code is reversing initial as well as setting reversed to the result, so you have two identical (reversed) arrays. Instead, use .slice() to duplicate the initial array, and reverse that instead.
var arr = [1,2,3,4];
for(var len = arr.length; len; len--)
arr.push(arr[len - 1]);
console.log(arr);
I don't recommend you mess with Array.prototype but here is what you want:
Array.prototype.duplicateAndReverse = function() {
let res = this.slice(); // create another copy so the original array will stay intact
for(var len = res.length; len; len--)
res.push(res[len - 1]);
return res;
}
let arr = [1, 2, 3, 4];
console.log(arr.duplicateAndReverse());
The problem was that you tried to reverse the initial array in place.Use the following optimized solution:
Array.prototype.duplicateAndReverse = function() {
return this.concat(this.slice().reverse());
}
console.log([1,2,3,4].duplicateAndReverse());
To retain the original array and create its reversed copy use Array.prototype.slice() function combined with Array.prototype.reverse() function
This is your problem because reverse() also reverse the original array
arr
var arr = [1,2,3,4]
var dup = arr.reverse()
console.log(arr) // => [4, 3, 2, 1]
console.log(dup) // => [4, 3, 2, 1]
You need to clone the original array first
var dup = arr.slice().reverse()
And then you can concat the 2 arrays to get the result. Happy coding!
Oriental solution, hihi.
var arr = [1,2,3,4];
var newArr = [];
arr.forEach((_,i) => newArr.unshift(arr[arr.length-i-1]) && newArr.push(arr[arr.length-i-1]))
console.log(newArr);

How to separate array of comma separated string into various arrays?

What's the best way to convert this array of comma separated values
[ 'com--test,LFutx9mQbTTyRo4A9Re5ksjdnfsI4cKN4q2,on',
'com--fxtrimester,SEzlksdfMpW3FxkSbzL7eo5MmqkPczCl2,on',
'com--fxtrimester,LFutx9mQbTTyRoldksfns4A9Re5I4cKN4q2,on' ]
Into three arrays?
[ 'com--test', [ LFutx9mQbTTyRo4A9Re5Ilsdf4cKN4q2', ['on',
'com--fxtrimester', SEzMpW3FxkSbzL7eo5MmlkdfqkPczCl2', 'on',
'com--fxtrimester' ] LFutksdfx9mQbTTyRo4A9Re5I4cKN4q2 ] 'on']
I was trying something like:
var indexToSplit = unique.indexOf(',');
var status = unique.slice(3, indexToSplit - 1);
var use = unique.slice(2, indexToSplit - 2);
var pros = unique.slice(0, indexToSplit - 3);
console.log(pros);
But I figured that is wrong ... any help is appreciated!
You will have to loop over array and use string.split to get seperate parts.
Once you have seperate parts, you can push them to necessary array;
var d = [ 'com--test,LFutx9mQbTTyRo4A9Re5ksjdnfsI4cKN4q2,on',
'com--fxtrimester,SEzlksdfMpW3FxkSbzL7eo5MmqkPczCl2,on',
'com--fxtrimester,LFutx9mQbTTyRoldksfns4A9Re5I4cKN4q2,on'];
var result = [[],[],[]];
var len = 3;
d.forEach(function(str, i){
var _tmp = str.split(',');
for (var i = 0; i<len; i++){
result[i].push(_tmp[i])
}
})
console.log(result)
A little generic way.
Loop over data and split each string using comma(,)
Loop over split values and check if necessary array exists.
If not, initialise array, but you cannot do p[i] = [] as this will push to first value. You will have to also initialise all previous values. For this, you can use new Array(length). By default, if length is greater than 0, all indexes will be initialise to undefined.
Now push to necessary array. Position will be maintained.
var d = ['com--test,LFutx9mQbTTyRo4A9Re5ksjdnfsI4cKN4q2,on',
'com--fxtrimester,SEzlksdfMpW3FxkSbzL7eo5MmqkPczCl2,on',
'com--fxtrimester,LFutx9mQbTTyRoldksfns4A9Re5I4cKN4q2,on,test'
];
var result = d.reduce(function(p, c, index) {
var _tmp = c.split(',');
for (var i = 0; i < _tmp.length; i++) {
// Check if position not defined.
if (p[i] === undefined)
// Initialize array and add default (undefined) to all elements before current element
p[i] = new Array(index);
p[i].push(_tmp[i])
}
return p;
}, [])
console.log(result)
With map this becomes:
for positions X out of 0, 1 and 2:
convert each item in the list into an array, and choose the Xth item
var start = [ 'com--test,LFutx9mQbTTyRo4A9Re5ksjdnfsI4cKN4q2,on',
'com--fxtrimester,SEzlksdfMpW3FxkSbzL7eo5MmqkPczCl2,on',
'com--fxtrimester,LFutx9mQbTTyRoldksfns4A9Re5I4cKN4q2,on' ]
var out = [0,1,2].map(i =>
start.map(x => x.split(',')[i]) )
console.log(out)
Since your question does not ask for a more general case, i am safely assuming it for 3 array. We can use forEach function on array below code can be one amongst the possible solutions
var arr1 = [];
var arr2 = [];
var arr3 = [];
var x = ['com--test,LFutx9mQbTTyRo4A9Re5ksjdnfsI4cKN4q2,on', 'com--fxtrimester,SEzlksdfMpW3FxkSbzL7eo5MmqkPczCl2,on', 'com--fxtrimester,LFutx9mQbTTyRoldksfns4A9Re5I4cKN4q2,on']
x.forEach(function(data) {
var dataArray = data.split(',');
arr1.push(dataArray[0]);
arr2.push(dataArray[1]);
arr3.push(dataArray[2]);
});
console.log(arr1)
console.log(arr2)
console.log(arr3)

How can i delete something out of an array?

My problem is that i have to delete something out of an array. I found out how to delete something out of a listbox. But the problem is that the listbox is filled by an array. So if I don't delete the value (I deleted out of the listbox) out of the array. The value keeps coming back when you add a new item. BTW: I am new to php and javascript.
My code is:
function removeItem(veldnaam){
var geselecteerd = document.getElementById("lst"+veldnaam).selectedIndex;
var nieuweArray;
alert(geselecteerd);
alert(document.getElementById(veldnaam+'hidden').value);
For (var i = 0, i<= arr.lenght, i++) {
If (i= geselecteerd){
nieuweArray = arr.splice(i,1);
document.getElementById(veldnaam+'hidden').value = arr;
}}
document.getElementById("lst"+veldnaam).remove(geselecteerd);
}
Use the delete operator. I'm assuming you are using objects as associative arrays.
var arr = {
"hello": "world",
"foo": "bar"
}
delete arr["foo"]; // Removes item with key "foo"
You can delete elements in an array using the delete command. But it will just set the value to undefined.
var arr = ['h', 'e', 'l', 'l', 'o'];
delete arr[2];
arr => ['h', 'e', undefined, 'l', 'o'];
So it will not remove the item, and make a shorter array, the array will still have 5 elements (0 to 4), but the value has been deleted.
In the case of "associative" arrays, or objects: The property will get erased and it will no longer exist.
var obj = { 'first':'h', 'second':'e', 'third':'l'};
delete obj['first'];
obj => { 'second':'e', 'third':'l'};
Add the following code somewhere
// Array Remove - By John Resig (MIT Licensed)
Array.prototype.remove = function(from, to) {
var rest = this.slice((to || from) + 1 || this.length);
this.length = from < 0 ? this.length + from : from;
return this.push.apply(this, rest);
};
and call it like this:
// Remove the second item from the array
array.remove(1);
// Remove the second-to-last item from the array
array.remove(-2);
// Remove the second and third items from the array
array.remove(1,2);
// Remove the last and second-to-last items from the array
array.remove(-2,-1);
Article containing the code above and explanation: http://ejohn.org/blog/javascript-array-remove/
var geselecteerd = document.getElementById("lst"+veldnaam).selectedIndex;
var nieuweArray;
var teller = 0;
var oudeArray=document.getElementById(veldnaam+'hidden').value;
var tmpArr="";
nieuweArray=oudeArray.split(":");
for (i = 0; i<nieuweArray.length; i++){
if (!(i==geselecteerd)){
tmpArr = tmpArr+nieuweArray[i]+":";}
teller++;
}
tmpArr = tmpArr + ":";
tmpArr = tmpArr.replace("::","");
document.getElementById(veldnaam+'hidden').value = tmpArr;
document.getElementById("lst"+veldnaam).remove(geselecteerd);
}
This is my solution and it worked. Thanks for your help.

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