var num = 10;
document.write('<p>num : ' + num + '</p>');
// 値を加算して変数に代入
num += 5; //num = num + 5
document.write('<p>num += 5 : ' + num + '</P>');
js_cc_01_assignment
-------------------
A [Pen](https://codepen.io/m-shinkawa/pen/BVNNLK) by [m-shinkawa](https://codepen.io/m-shinkawa) on [CodePen](https://codepen.io).
[License](https://codepen.io/m-shinkawa/pen/BVNNLK/license).
js_assignment
-------------
A [Pen](https://codepen.io/m-shinkawa/pen/BVNNLK) by [m-shinkawa](https://codepen.io/m-shinkawa) on [CodePen](https://codepen.io).
[License](https://codepen.io/m-shinkawa/pen/BVNNLK/license).