CODEWITHSUNDEEP
javascript
udexter
udexter

Reputation: 2347

Obtaining the position (first and last) of a specific value that is not null in a array

I'have the next array:

[null,null,null,null,null,null,2,10,29,43,45,40,54,39,13,1,null,null,null,null,null]

I need to know what is the first position in that array that is NOT null and the last that is NOT null too.

In this particular example, first will be 6 (counting 0 as position 1) and 15.

Thank you

Upvotes: 0

Views: 77

Answers (2)

Joe
Joe

Reputation: 82594

Using non-standard array methods:

var arr = [null,null,null,null,null,null,2,10,29,43,45,40,54,39,13,1,null,null,null,null,null];

var mapped = arr.map(function (i) {
    "use strict";    
    return i !== null;
}); 

var first = mapped.indexOf(true);
var second = mapped.lastIndexOf(true);

Both map and indexOf and lastIndexOf require IE9+ browsers or shims. However, they do look really cool.

Upvotes: 2

ThiefMaster
ThiefMaster

Reputation: 318498

var firstPos = -1, lastPos = -1;
for(var i = 0; i < arr.length; i++) {
    if(arr[i] !== null) {
        if(firstPos == -1) {
            firstPos = i;
        }
        lastPos = i;
    }
}

Upvotes: 3

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