Unable to access VARIABLE inside index.html file

I am not able to access my variable provided in the plugin like this

```
new InterpolateHtmlPlugin({
MYVAR: 'myvariable',
}),
```
Here I am accessing variable like this
I want inside script like this
```

if(%MYVAR%) {
do something
}

```

**software version**
windows 10
browser chrome 76.0.3809.132
webpack 4
react 16+