I'm having issues with some code. I'm trying to add an element to the end of a 2d array, but the log is returning the length of the array.
var arr = [["a"],["b"],["c"],["d"]];
var arr2 = arr.push(["e"]);
Logger.log(arr2);
arr2 is returning "5" but would like it to return the array with the pushed element at the end of this array.
Values will be pushed in the same memory reference, return type of push method is integer, (length of the array)
Please do like this, your results will be achieved
var arr = [["a"],["b"],["c"],["d"]];
arr.push(["e"]);
Logger.log(arr);
The push() method adds one or more elements to the end of an array and returns the new length of the array, so you just need to log the initial array.
var arr = [
["a"],
["b"],
["c"],
["d"]
];
arr.push(["e"]);
console.log(arr);
This question already has answers here:
From an array of objects, extract value of a property as array
(24 answers)
Closed 4 years ago.
I have array1 that contains 1 char in each element.
What I need, is to get the value of array1[i].charCodeAt(); and put it in array2.
Easy to do it, with a for statement.
for(i=0;i<10;i++){
y[i]= x[i].charCodeAt();
}
I did some research but nothing that explain this case:
Is it possible to populate array2 by some sort of destructuring, or what I am asking is not supported in js? For example:
array1 =['a','b','c'];
array2 = [];
array2 = array1[].charCodeAt.
conole.log('The first char has code ' + array2[0]); // The first letter has code 97.
You aren't creating separate standalone variables, so destructuring isn't what you're looking for - but, you can use .map to transform the first array into the second:
const array1 =['a','b','c'];
const array2 = array1.map(char => char.charCodeAt(0));
console.log(array2);
You can use Array.prototype.map():
const array1 = ['a','b','c'];
const array2 = array1.map(c => c.charCodeAt());
console.log(array2);
I am trying to add array of arrays dynamically in javascript. I need the data in the following format -
var dataArray = [[],[],[],.....,[]];
How can I initialize this kind of array? Suppose if I have three arrays to be added, I can initialize as follows -
var dataArray = [[],[],[]];
This will accept only three records to be added. But, what should I do in case of adding large number of arrays? Here I cannot know the amount of data I get as input.
I have tried using concat() and merge() methods, these are adding contents directly in to a single array, but that is not what I wanted.
Can any one please help me out on this?
You can build or add an array into an array like this:
var dataArray = [];
dataArray.push([1,2,3]);
dataArray.push([3,4,5]);
console.log(dataArray); // [[1,2,3], [3,4,5]]
Or, if you want to add elements to the sub-arrays:
var dataArray = [];
dataArray.push([1,2,3]);
dataArray.push([3,4,5]);
dataArray[0].push(4);
dataArray[1].push(9);
console.log(dataArray); // [[1,2,3,4], [3,4,5,9]]
You initialize a sub-array by assigning an array to the element of the outer array. You can then use array operations directly on the sub-array element:
// create a sub-array element
dataArray[2] = [];
dataArray[2].push(8);
dataArray[2].push(7);
console.log(dataArray[2]); // [8,7]
console.log(dataArray); // [[1,2,3,4], [3,4,5,9], [8,7]]
The key thing it appears you don't understand is that an array of arrays is just that. It's an outer array where each element in the outer array is itself an array. You use ordinary array methods to operate on either the outer array or the inner arrays. To operate on an inner array, you fetch that element from the outer array and then just treat it as an array. For example:
var dataArray = [];
dataArray.push([1,2,3]);
dataArray.push([3,4,5]);
console.log(dataArray); // [[1,2,3], [3,4,5]]
var innerArray = dataArray[0];
console.log(innerArray); // [1,2,3]
innerArray.push(12);
console.log(innerArray); // [1,2,3,12]
innerArray.legnth = 2;
console.log(innerArray); // [1,2]
innerArray.push(9,8,7);
console.log(innerArray); // [1,2,9,8,7]
innerArray.splice(1,2);
console.log(innerArray); // [1,8,7]
You have wrote "I am trying to add array of arrays dynamically in javascript"
The simple way is using Array.prototype.push method:
var arr1 = [1,2], arr2 = [3,4], arr3 = [5,6], arr4 = [7,8], arr5 = [9,10],
dataArray = [];
[].push.apply(dataArray, [arr1, arr2, arr3, arr4, arr5]);
console.log(JSON.stringify(dataArray, 0, 4));
The console.log output:
[
[
1,
2
],
[
3,
4
],
[
5,
6
],
[
7,
8
],
[
9,
10
]
]
There are tons of way you can do this. A simple one could be
var arrayN = n => Array(n).fill([])
document.write("<pre>" + JSON.stringify(arrayN(10)) + "</pre>")
On another thinking if you already have arrays of arrays then the most simplified way of concatenating them in place should be using the new spread operator like;
var arr = [[1,2,3],[1,3,5]],
brr = [[3,2,1],[7,8,9]];
arr.push(...brr);
document.write("<pre>" + JSON.stringify(arr) + "</pre>");
I am trying to make a copy of a javascript array and modify the 'copy' without modifying the original variable too, can anyone explain what I am doing wrong..
e.g
var array1 = [2, 5];
var array2 = '';
array2 = array1;
array2.pop();
console.log(array1);
console.log(array2);
// both output the same, however I want it to show array1 with 1 single item
I am trying to make it so array2 will only contain the one item in the array & array1 will contain two items in the array. Any ideas what I'm doing wrong?
In order to create a copy of an array rather than assign the reference value you can use the .slice method.
array2 = array1.slice(0);
Slice returns a (shallow) copy of the given array from the given index to the (optional end index)
Use slice() to copy the array.
var array1 = [2, 5];
var array2 = '';
array2 = array1.slice(0);
array2.pop();
console.log(array1);
console.log(array2);
slice does not alter the original array, but returns a new "one level
deep" copy that contains copies of the elements sliced from the
original array.
Documentation
It is as simple as using the slice function:
var array1 = [2, 5];
var array2 = '';
array2 = array1.slice();
array2.pop();
console.log(array1);
console.log(array2);
Here you are telling javascript to get a copy of the elements in array1 and assign the result to array2. By not setting the start and ending position it will slice the whole array.
When you writing this
array2 = array1 //It creates reference on array1 object
array2.pop() // removes 5 from both end
So you have to clone one array to another by slice() method---
array2 = array1.slice(0) // cloning array1 's element to array2
array2.pop() // removes 5 from only array2 not from array1
Now it works fine
Alter the line array2 = array1; to:
array2 = array1.slice(0);
Slice method returns a (shallow) copy of the given array from the given index to the (optional end index)
I hope this helps.
var array1 = [column1,column2,column3,column4];
var array2 = [column1 [empid],column2 [mobno],column4 [place]];
if array1 has any of array2 values. I mean, in above case column1,column2,column4 is there in array1, then remove those values and array1 should have only column3 and then append array1 value with array2.
after check and remove, now array1 = [column3] then append array1 value with array2 and finally
array2 = [column1 [empid],column2 [mobno],column3,column4 [place]]; it should be in correct index position
is above case possible?
I would recommend using a library like Underscore.js, it has functions like _.union() that would do what you described. If you don't want to the library you could have a look at their implementation.
Using your example:
array2 = _.union(array1, array2);
if you dont want to use any library then you can do
for(elem in array2){
var index = array1.indexOf(array2[elem]);
if(index > -1)
array1.splice(index,1);
}
array2 = array1.concat(array2).sort();