How to make a script to resize image to fit exact frame?

Good afternoon,

My friend is working on a task to make multiple images fit the frame size 500x700 px.

We work out this script, though it sometimes makes Height above 700 px.

Can anyone help to edit it?

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doc = app.activeDocument; 

doc.changeMode(ChangeMode.RGB); 

var fWidth = 500;

var fHeight = 700;

if (doc.width > fWidth,"px") {

    doc.resizeImage(UnitValue(fWidth,"px"),null,null,null,ResampleMethod.BICUBIC);

}

else {

    doc.resizeImage(null,UnitValue(fHeight,"px"),null,null,ResampleMethod.BICUBIC);

}

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