JavaScript - Check if one array has the same index from a second array

Question

Let's say I have an object of

var people = [
  {name: 'John'}, // 0
  {name: 'James'}, // 1
  {name: 'Sue'}, // 2
  {name: 'Mary'}, // 3
  {name: 'Will'}, // 4
  {name: 'Lukas'}, // 5
  {name: 'Sam'} // 6
];

and then I have this array: var history = [0, 2, 4, 6]; // we have John, Sue, Will and Sam

Using Lodash, or general JavaScript, how can I make it to return true or false if a entered value is found inside the history[] array.

For example, isInHistoryArray(5) would return false but isInHistoryArray(2) would return true

Maybe you mean array comparing, check this answer1, answer2

Anna Gabrielyan
– Anna Gabrielyan

2016-02-14 18:46:09 +00:00
Commented Feb 14, 2016 at 18:46 — Anna Gabrielyan
– Anna Gabrielyan, Commented Feb 14, 2016 at 18:46

Daniel Mizerski · Accepted Answer · 2016-02-14 18:50:59Z

2

For example

You have list-array of players in the small game:

var people = [
  {name: 'John'},
  {name: 'James'},
  {name: 'Sue'},
  {name: 'Mary'},
  {name: 'Will'},
  {name: 'Lukas'},
  {name: 'Sam'}
];

And you have array of the... actually connected people:

var history = [0, 2, 4, 6];

Okay, lets say that both containers are in the global scope for comfort.

You can check it by this function body

function checkHistory(a){
for(var i = 0; i < history.length; i++){
   if(history[i] === a) return true;
}return false;}

answered Feb 14, 2016 at 18:50

Daniel Mizerski

1,1311 gold badge8 silver badges24 bronze badges

Sign up to request clarification or add additional context in comments.

1 Comment

Daniel Mizerski Over a year ago

Bacause it can be modded to make it automatic from any other data and returning auto name of record or sth.

Mehdi Dehghani · Accepted Answer · 2016-02-14 18:47:39Z

2

You can just use `includes' method

history.includes(5) // false
history.includes(0) // true

answered Feb 14, 2016 at 18:47

Mehdi Dehghani

11.7k6 gold badges64 silver badges68 bronze badges

2 Comments

T.J. Crowder Over a year ago

Arrays have no includes method (yet), just strings. history is an array.

T.J. Crowder Over a year ago

Array#includes is a Stage 4 ES2016 proposal, which V8 implements. It's not broadly available yet, nor is the spec completed. It should be in the spec when it comes out, Stage 4 means "ready to include in the spec," but you need a cutting-edge JavaScript engine (or a polyfill) to use it.

T.J. Crowder · Accepted Answer · 2016-02-14 18:45:16Z

1

Arrays have an indexOf method that compares what you give it against the entries in the array (using strict comparison, ===) and tells you the index of the first match, or -1 (specifically) if there is no match. So:

function isInHistoryArray(value) {
    return history.indexOf(value) !== -1;
}

In ES2015, there are also Array.find and Array.findIndex (both of which can be polyfilled on older engines) that let you supply a predicate callback, but you don't need that here as your entries are numbers and what you're checking is also a number.

answered Feb 14, 2016 at 18:45

T.J. Crowder

1.1m201 gold badges2k silver badges2k bronze badges

Collectives™ on Stack Overflow

JavaScript - Check if one array has the same index from a second array

3 Answers 3

1 Comment

2 Comments

Comments

Your Answer

Linked

Hot Network Questions

Collectives™ on Stack Overflow

3 Answers 3

1 Comment

2 Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Linked

Related