How to pass variable in a variable in JavaScript?

Question

I want to define a variable that contains a variable. In this example the variable that I want to pass is "filldata".

I have tried passing it using $filldata as well as +filldata+.

if (fill == true) {
     $filldata = "fill: true,";
} else {
     $filldata = "fill: false,";
};

if (amount == true) {
        var set1 = {
            label: "Earnings",
            id: "earnings",
            data: data1,
            points: {
                show: true,
            },
            bars: {
                show: false,
                barWidth: 12,
                aling: 'center'
            },
            lines: {
                show: true,
                $filldata
            },
            yaxis: 1
        };
    } else {
        var set1 = "";
    }

You want to dynamically set a property on an object. In your example you can simply do lines: {show: true, fill: fill}. Alternative you can assign the name and the value to variables (e.g. key = 'fill'; value = true) and do lines: {show: true, [key]: value}. — Felix Kling
– Felix Kling, Commented Nov 4, 2016 at 20:59
Instead of using $filldata in your set object as you are now, why not just do fill: $filldata and set $filldata to true or false? — j08691
– j08691, Commented Nov 4, 2016 at 21:00
@FelixKling - Thank you! Your answer worked using - fill:fill. The answer below did not work since it does not work if fill=false. If you want to make an answer I will choose it as correct. — Scott Paterson
– Scott Paterson, Commented Nov 4, 2016 at 21:07

GPicazo · Accepted Answer · 2016-11-04 21:10:28Z

2

Since you are just trying to create a boolean property named 'fill' with the value of some variable, also called fill (using fussy truthy/falsy values), then you can just skip creating the intermediate $filldata variable altogether and just create the property with the value evaluated inline. It's more succinct and more obvious.

Try:

if (amount == true) {
    var set1 = {
        label: "Earnings",
        id: "earnings",
        data: data1,
        points: {
            show: true,
        },
        bars: {
            show: false,
            barWidth: 12,
            aling: 'center'
        },
        lines: {
            show: true,
            fill: fill==true
        },
        yaxis: 1
    };
} else {
    var set1 = "";
}

EDIT:

Also, note that it is not good practice to declare the variable set1 inside the if block scope if you intend to use it elsewhere. A better alternative would be:

var set1 = (amount == true) ?
    {...your object as defined above...}
    : "";

edited Nov 4, 2016 at 21:10

answered Nov 4, 2016 at 21:00

GPicazo

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1 Comment

Felix Kling Over a year ago

It would be more useful if you provided an explanation of the problem/solution, not just code and "try".

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