Find custom string index of an array by value - for multiple arrays

Question

I have a bit of a problem with arrays.

I have a string as value, which is unique to an array index, e.g. "daa12d956752gja2":

g_nodeMapping["87686479/welcome.html"] = "daa12d956752gja2";

This string is what I know. What I need to get is the index, so "87686479/welcome.html". The thing is... I have dozens of arrays like this. It basically looks like this:

g_nodeMapping = [];
g_nodeMapping["8374628/test.html"] = "489fa3682975da";
g_nodeMapping["8953628/anothersite.html"] = "gi764295hf46";
g_nodeMapping["267857543/helpplx.html"] = "8653468te87a";

...

I tried the indexOf method, but it doesn‘t seem to find the array index for the value after the equation sign.

I can‘t change the array unfortunately.

Help is much appreciated. Sorry for the formatting, I'm on mobile.

“ and „ will cause a SyntaxError in Javascript. You might consider using ' instead. — CertainPerformance
– CertainPerformance, Commented Jan 7, 2019 at 8:38
I think so... If I type in g_nodeMapping into the browser console it says „object array“ — schokogabel332
– schokogabel332, Commented Jan 7, 2019 at 8:43
try instead array object : g_nodeMapping = []; g_nodeMapping = {}; — Vadim Hulevich
– Vadim Hulevich, Commented Jan 7, 2019 at 8:43
As stated above, I can‘t change the array unfortunately :( — schokogabel332
– schokogabel332, Commented Jan 7, 2019 at 8:45

prasad_ · Accepted Answer · 2019-01-08 14:30:22Z

1

You can define a function findCustomKey that takes an array element (or value) as a parameter and returns the key. The following example shows that:

var arr = [];
arr["8374628/test.html"] = "489fa3682975da";
arr["8953628/anothersite.html"] = "gi764295hf46";
arr["267857543/helpplx.html"] = "8653468te87a";

function findCustomKey(ele) {
    let keys = Object.keys(arr);
    for (let keyEle of keys) {
        if (arr[keyEle] == ele) {
            return keyEle;
        }
    }
}

console.log(findCustomKey("489fa3682975da"));
console.log(findCustomKey("8653468te87a"));
console.log(findCustomKey("abcd123"));

The Output:

8374628/test.html
267857543/helpplx.html
undefined

Another Version (EDIT added):

Here is another way to code findCustomKey(the way to use it remains same):

function findCustomKeyV2(ele) {
    return Object.keys(arr).filter(k => arr[k] == ele)[0];
}

Another Version:

This version of the solution was added as the above code did not work on IE browsers. The following code worked on Firefox, Chrome and IE11 browsers.

var arr = [];
arr['8374628/test.html'] = '489fa3682975da';
arr['8953628/anothersite.html'] = 'gi764295hf46';
arr['267857543/helpplx.html'] = '8653468te87a';

var arrMap = new Map();
for (let k in arr) {
    arrMap.set(arr[k], k);
}

console.log(arrMap.get('489fa3682975da'));
console.log(arrMap.get('8653468te87a'));
console.log(arrMap.get('abcd123'));

edited Jan 8, 2019 at 14:30

answered Jan 7, 2019 at 9:57

prasad_

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3 Comments

schokogabel332 Over a year ago

It works on mozilla and chrome, but I get a SCRIPT5009 error in IE11 with edge compatibility. Any ideas why?

prasad_ Over a year ago

I had tried on Firfox and Chrome with no issues. I tried on the IE 11- I get the error SCRIPT1002: Syntax error. I searched the net (Google). There seems to no specific consistent reason, except the feature may not have been supported on the IE browser. There are various solutions in different contexts - I couldn't figure what the real issue is. If I find a proper reason I will post here.

prasad_ Over a year ago

@schokogabel332 I added alternative solution that worked on IE11 also. Please try and let me know - if possible.

Nina Scholz · Accepted Answer · 2019-01-07 08:45:02Z

1

You could find the key by getting all keys from the object/array and find the value.

function getKey(object, value) {
    return Object.keys(object).find(k => object[k] === value);
}
   
var g_nodeMapping = [];
g_nodeMapping["8374628/test.html"] = "489fa3682975da";
g_nodeMapping["8953628/anothersite.html"] = "gi764295hf46";
g_nodeMapping["267857543/helpplx.html"] = "8653468te87a";
g_nodeMapping["87686479/welcome.html"] = "daa12d956752gja2";

console.log(getKey(g_nodeMapping, "daa12d956752gja2"));

answered Jan 7, 2019 at 8:45

Nina Scholz

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1 Comment

schokogabel332 Over a year ago

Thank you, I tried the other answer and it works. Thank you vers much for your solution.

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