Remove duplicate values from an array of objects in javascript

Question

i have an array of objects like this:

arr = [
    {label: Alex, value: Ninja},
    {label: Bill, value: Op},
    {label: Cill, value: iopop}
]

This array is composed when my react component is rendered. The i user Array.prototype.unshift for adding a desired element in the top of my array. So i write arr.unshift({label: All, value: All}). When my component first rendered my array is successfully created as i desire. But when i rerender it it shows me the array with the value {label: All, value: All} as duplicate. To be more specific it is shown something like this:

arr = [
    {label: All, value: All},
    {label: All, value: All},
    {label: Alex, value: Ninja},
    {label: Bill, value: Op},
    {label: Cill, value: iopop}
]

How can i fix this? I tried the methods described in a specific topic here but it didn't work

Answer 1

You can use array#reduce and array#some.

const arr = [
    {label: 'All', value: 'All'},
    {label: 'All', value: 'All'},
    {label: 'Alex', value: 'Ninja'},
    {label: 'Bill', value: 'Op'},
    {label: 'Cill', value: 'iopop'}
]

var result = arr.reduce((unique, o) => {
    if(!unique.some(obj => obj.label === o.label && obj.value === o.value)) {
      unique.push(o);
    }
    return unique;
},[]);
console.log(result);