I am new to JavaScript and want to process the following array -
var a = [
"John-100",
"Mark-120",
"John-50",
"Mark-130"
]
into the following format -
a = {
"John": [100, 50],
"Mark": [120, 130]
}
But have been unable to do so. Any help will be very much appreciated.
Edit - Any other format ideas where the marks of a particular student can be grouped together are also welcome.
Here is one way to achieve what you described:
var a=[
"John-100",
"Mark-120",
"John-50",
"Mark-130"
]
function convertToSpecialObject(input) {
//setup the output as an empty object
const output = {};
// iterate through input array one element at a time
input.forEach(e => {
// split the current element by dividing it into part[0] before the dash
// and part[1] after the dash sign
const parts = e.split(/-/);
// now check the output object if it already contains a key for the part before the dash
if(!output[parts[0]]) {
// in this case, we don't have a key for it previously
// so lets set it up as a key with an empty array
output[parts[0]] = [];
}
// we must have already created a key or there is a key in existence
// so let's just push the part after the dash to the current key
output[parts[0]].push(Number(parts[1]));
});
// work done
return output;
}
const b = convertToSpecialObject(a);
console.log(b);
you can achieve this by using reduce and split method
var a=[
"John-100",
"Mark-120",
"John-50",
"Mark-130"
]
const b = a.reduce((acc, val) => {
const _split = val.split('-');
const name = _split[0]
if(acc && acc[name]) {
acc[name].push(+_split[1])
} else {
acc[name] = [+_split[1]]
}
return acc;
}, {});
console.log(b)You can achieve it in a very simple way by just using a Array.forEach() method along with the String.split().
Live Demo :
var a = [
"John-100",
"Mark-120",
"John-50",
"Mark-130"
];
const obj = {};
a.forEach(element => {
if (!obj[element.split('-')[0]]) {
obj[element.split('-')[0]] = [];
}
obj[element.split('-')[0]].push(element.split('-')[1])
});
console.log(obj);With Simple Approach
const input = [
"John-100",
"Mark-120",
"John-50",
"Mark-130"
];
const getCustomObject = (arr) => {
const obj = {};
for (let i = 0; i < arr.length; i++) {
const split = arr[i].split('-'); //spliting with '-'
if (obj[split[0]]) {
//push to existing array
obj[split[0]].push(split[1]);
} else {
obj[split[0]] = []; //initilize array if no member
obj[split[0]].push(split[1]);
}
};
return obj;
}
console.log(getCustomObject(input));
Now numbers are not numerical values, It can be achieved with parseInt or parseFloat
As I suggested, string split, and array reduce - add in an array map and it's a single line of code
let a=["John-100","Mark-120","John-50","Mark-130"];
a=a.map(v=>v.split('-')).reduce((r,[n,m])=>({...r,[n]:[...r[n]||[],+m]}),{});
console.log(JSON.stringify(a));The only answer with the correct result ... an array of NUMBERS
varmakes me wonder if you're bound to an older version of javascript. Also Are you sure you want to reassign the new object to the same variable? Could clarify these things?