Javascript: How do I pass the value (not the reference) of a variable to a function?

Question

Here is a simplified version of something I'm trying to run:

for ( winDoorNo = 0; winDoorNo < aWinDoorSetSpec.no_of_winDoors; winDoorNo ++ ) {
    (function (winDoorNo, self) {

        self.tangentVectors_azimuth = [];
        self.tangentVectors_polar   = [];

        self.tangentVectors_azimuth[winDoorNo] = tangentPlane.tangentVector_azimuth;
        self.tangentVectors_polar[winDoorNo]   = tangentPlane.tangentVector_polar;

    })(winDoorNo, this);
}

but I'm finding that the self.tangentVectors_azimuth array only contains a value on the last value that the for loop index variable had. I found this post describing a similar problem and I implemented the suggested solution which is to use a closure. However this does not work for me. After the for loop has executed, the value of this.tangentVectors_azimuth is still:

[undefined, undefined, Object { x=0.01999999996662183, y=0.01599999957331022, z=0, more...}]

Answer 1

You are creating new arrays for each iteration in the loop, so each time you will throw away the previous result.

Create the arrays outside the loop:

this.tangentVectors_azimuth = [];
this.tangentVectors_polar = [];
for (winDoorNo = 0; winDoorNo < aWinDoorSetSpec.no_of_winDoors; winDoorNo++) {
  this.tangentVectors_azimuth[winDoorNo] = tangentPlane.tangentVector_azimuth;
  this.tangentVectors_polar[winDoorNo] = tangentPlane.tangentVector_polar;
}