Need help looping JSON with JavaScript. Weird behaviours

Question

Although, it ran fine on small data. I need help looping through JSON in this form:

var current_value = 2;
json_data = {"2":"first information","3":"Second informaton","4":"Third information"}

What I want to do is get the value in the json_data that corresponds to current_value of 2 The problem is that I keep getting " anytime I run this loop:

for(x in json_data){
    if(x === current_value){
        extracted = json_data[current_value];
    }
}

It's not actually Json you have there, it's an object literal. — Keith
– Keith, Commented Oct 4, 2017 at 12:38
@Keith unless it is actually a JSON string and they're not parsing it, may be why they are getting " — George
– George, Commented Oct 4, 2017 at 12:39
You loop through all keys, and if the current key equals a predetermined value, you take the predetermined value out of the object… The entire loop is superfluous for doing that. — deceze
– deceze ♦, Commented Oct 4, 2017 at 12:40
@George — If that is the case, then their code example does not represent their real code. — Quentin
– Quentin, Commented Oct 4, 2017 at 12:40

Quentin · Accepted Answer · 2017-10-04 12:39:53Z

2

JavaScript property names are strings. 2 is a number. === does not do type conversion. "2" !== 2.

You should set current_value to "2" instead of 2.

The loop is pointless though.

A more sensible approach would be:

var extracted;
if (current_value in json_data) { 
    extracted = json_data[current_value];
}

… or even just skip the if statement. extracted will be undefined either way if the property doesn't exist.

answered Oct 4, 2017 at 12:39

Quentin

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