Minified JS causes use of variable before initialization

[masonfrykman]

Hey! I tried to minify some JS code and Chrome gave me a fun Uncaught ReferenceError: Cannot access '_B' before initialization when I ran it.

This is the source code before it was minified

let degI = degFloor + degGrowthFactor * i
while(degI > 360) {
    degI -= 360
}

// find the x & y extensions
let theta = (degI * Math.PI) / 180 // convert degrees to radians
let a = lineLength * Math.sin(theta) // this will be the y extension
let b = lineLength * Math.cos(theta) // this will be the x extension

This is the problematic code after minification

let _a = _i + J * i
, a = E * Math.sin(_B)
, b = E * Math.cos(_B);
while (_a > 360)
    _a -= 360;
let _B = (_a * Math.PI) / 180;

F.Y.I, this was generated w/ v15.2.0
Also for more context, the code is inside a for loop, if y'all need the entire file I can provide it,,,

Thanks :)

[coderaiser]

Looks like the issue with rule minify/merge-variables

[coderaiser]

Try to set config .minify.json to:

{
    "js": {
        "type": "putout",
        "putout": {
            "mergeVariables": false
        }
    }
}

It is works for you?

[coderaiser]

Just updated @putout/plugin-minify, the safest way to handle this would be to avoid merging variables when there is AssignmentExpression in the block, so now code should look like this:

let A=degFloor+degGrowthFactor*i;while(A>360)A-=360;let _=(A*Math.PI)/180;let a=lineLength*Math.sin(_);let b=lineLength*Math.cos(_);

Please re-install Minify and tell me if it works for you now

[masonfrykman]

Updated, the order is corrected and everything is working now! Thank you :)