Javascript - set a variable using concatenation of strings [duplicate]

Answer 1

This is possible but you have to be wary of context and scope.

1. To set variable with global scope in browser environment:

window[str1 + str2] = value

2. To set variable with global scope in node environment:

global[str1 + str2] = value

3. Within a closure and scoped within that closure:

this[str1 + str2] = value

Within the closure, global and window will still set the global. Note that if you are within a function that is being called, 'this' could refer to another object.

Answer 2

You can set a global variable this way:

window[first + "_" + second] = "set this as the new variable";

and access it as:

console.log(group_read);

Answer 3

It's not clear exactly what you're trying to accomplish, but you can access variables by name as properties of an object.

// this is the container to hold your named variables 
//    (which will be properties of this object)
var container = {};

function setVariableIndirectly(obj){
    var second = obj.className; // returns "read"
    var first = obj.parentNode.className; // returns "group"

    // this is how you access a property of an object 
    //    using a string as the property name    
    container[first + "_" + second] = "set this as the new variable";

   // in your example container["read_group"] would now be set
}

It's probably better to put your variables on your own container object as shown above, but you can also access global variables via properties on the window object.