Javascript splitting string by given array element

Question

I have given string "asdlfjsahdkljahskl" and have given array [1,2,3,1,7,2,1,2].My final output should be a, sd, lfj, s, ahdklja, hs, kl.

I know how to split the string but I don't know how to compare the string and cut according to given array

HTML Code

<button onclick="myFunction()">click me</button>
<p id="demo"></p>

JavaScript

var width = [1,4,2,6,1,1,10,1];
function myFunction() {
 var str = "abcdefghijklmnopqrstuvwxyz";
 var res = str.split("");
 for(var j=0; j.length;j++){
 document.write(width[j]);
 }
 document.getElementById("demo").innerHTML = res;
 }

Thank you for your help

• dana: j.length does not make any sense since it is a number.
• Kasia: you can keep the loop. You will need array for result and local variable keeping rest of the string after sub
• Redu: Your expected output is probably wrong...

Answer 1

You could slice the string with a stored value and a new length.

var string = "asdlfjsahdkljahskl",
 array = [1, 2, 3, 1, 7, 2, 1, 2],
 p = 0,
 result = array.map(function (a) {
 return string.slice(p, p += a);
 });
console.log(result);

The same with a for loop

var string = "asdlfjsahdkljahskl",
 array = [1, 2, 3, 1, 7, 2, 1, 2],
 p = 0,
 i = 0,
 result = []
for (i = 0; i < array.length; i++) {
 result.push(string.slice(p, p + array[i]));
 p += array[i];
}
console.log(result);

• danny: how would this be possible without .map
• mhodges: @danny you can use any iterator, honestly (assuming you use them properly) - my answer uses .forEach() if you are interested in that one
• danny: I am beginner, so I am looking very simple logic not using for each or .map. Thanks for helping

Answer 2

var string="asdlfjsahdkljahsxkl",
 array=[1,2,3,1,7,2,1,2];
function myFunction() {
array.forEach(function(index){
 var yourvalue=string.slice(0,index);
 console.log(yourvalue);
 document.getElementById("demo").innerHTML += yourvalue+'\n';
 string=string.slice(index,string.length);
});
 }

<button onclick="myFunction()">click me</button>
<p id="demo"></p>

Answer 3

An alternative to Nina's answer is to convert your string to an array, like you have done, and use the .splice() function like so:

var str = "asdlfjsahdkljahskl",
 arr = [1, 2, 3, 1, 7, 2, 1, 2];
function extractValues (str, strLens) {
 str = str.split("");
 strLens.forEach(function (strLen) {
 console.log(str.splice(0, strLen).join(""));
 });
}
extractValues(str, arr);

• danny: what does .foreach do ? does it compare every array element. I am running on my local editor is giving me error
• mhodges: @danny developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/…