Here's my code:

function loadTexture() {
    textureImage = new Image();

    textureImage.onload = function() {
        setupTexture();
    }

    textureImage.src = "jumper2.png";
}

function setupTexture() {
    texture = gl.createTexture();

    gl.bindTexture(gl.TEXTURE_2D, texture);
    gl.pixelStorei(gl.UNPACK_FLIP_Y_WEBGL, true);

    // this next line has the error: Uncaught SecurityError: An attempt was made to break through the security policy of the user agent.
    gl.texImage2D(gl.TEXTURE_2D, 0, gl.RGBA, gl.RGBA, gl.UNSIGNED_BYTE, textureImage);
    gl.texParameteri(gl.TEXTURE_2D, gl.OES_TEXTURE_FLOAT_LINEAR, gl.NEAREST);

    if (!gl.isTexture(texture)) {
        alert("Error: Texture is invalid");
    }

    glProgram.samplerUniform = gl.getUniformLocation(glProgram, "uSampler");
    gl.uniform1i(glProgram.samplerUniform, 0);
}

I've researched it and it is a CORS error a "Cross-origin resource sharing" error, but it's a local file! I can't figure out what's wrong.

I did make the picture using gimp, and I'm not sure the coding was right on the export, but I eliminated a previous error using "gl.OES_TEXTURE_FLOAT_LINEAR".