Why isn’t this variable working

Question

I’m trying to practice using the canvas since I’ve never used it before, so I tried just drawing a line. When I run it though, it says it can’t find a variable context in line 6.
window.onload = function(){
var canvas=
document.getElementById("canvas");
var context= canvas.getContext("2d")
};
context.moveTo(10,10);
context.lineTo(100,10);
context.stroke();

Answer 1

Put everything inside the onload function

Answer 2

ElizabethM

Code outside the window.onload function is executing first. That's why.

Answer 3

// alert 2, alert 1

window.onload = function(){
alert(1);
var canvas=
document.getElementById("canvas");
var context= canvas.getContext("2d")
};
alert(2);
context.moveTo(10,10);
context.lineTo(100,10);
context.stroke();