get variable name into string in javascript

Yes, you can do it:

function getVariableName(v) {
    for (var key in window) {
        if (window[key] === v)
            return key;
    }
}
var abc = '123';
var def = '456'
alert ("value of " + getVariableName(abc) +" is "+ abc +" and value of " + getVariableName(def) + " is " + def);

Use the code below.

const abc = '123';
const def = '456';

const varToString = varObj => Object.keys(varObj)[0]

alert ("value of " +varToString({def}) +" is "+ def +" and value of " +varToString({abc})+" is "+abc );

What this basicly does is, you pass the variable to varToString as an object using {variable}. varToString then returns an array with the passed variable as value.

[
  "abc"
]

We grab this value using the [0] selector (Object.keys(varObj)[0]). Now it returns

abc