Code below will return me the first index of the object with id = "1" which is 0. How to find the last index of the object with id = "1" which is 2 ? Of course I could use a loop but without using a loop is it possible?
var array = [{id: "1"}, {id: "2"}, {id: "1"}];
var index = array.findIndex(function(oItem) {
return oItem.id === "1";
});
You can map() you array to just array of ids and then use lastIndexOf
var array = [{id: "1"}, {id: "2"}, {id: "1"}];
var lastIndex = array.map(e => e.id).lastIndexOf('1')
console.log(lastIndex)Since currently there is no findLastIndex method and you don't want to use loop you could create your own function using recursion that you can pass anonymous function as parameter to search by.
var array = [{id: "1"}, {id: "2"}, {id: "1"}];
function findLastIndex(data, func) {
var start = data.length - 1;
var result = null;
function search(data, i, func) {
if (i < 0) return;
var check = func(data[i]);
if (check == true) {
result = i;
return;
}
search(data, i -= 1, func)
}
search(data, start, func)
return result;
}
var lastIndex = findLastIndex(array, function(e) {
return e.id == 1;
})
console.log(lastIndex)
map is also a loop, isn't it?Map, where the key is the ID and the value is an array of matches for that ID. If you need lookups on other properties too, then you'll want to take that into account.You could use Array#map and declare new index variable, which would be overwrited until it reaches the last element with given id.
var array = [{id: "1"}, {id: "2"}, {id: "1"}],
index;
arr = array.map((v,i) => v.id == 1 ? index = i : null);
console.log(index);Try this using Array map() method :
var myarray = [{id: "1"}, {id: "2"}, {id: "1"}];
var res = myarray.map(function(item) {
return item.id;
});
console.log(res.lastIndexOf("1"));If you don't mind using lodash, it has findLastIndex.
If anything, you can look at the source of it for ideas.
