交互式窗口使您能够通过任意表达式评估来启动调试流程。

The interactions window lets you start a debugging process through an arbitrary expression evaluation.

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如果使用必须CSS表达式请记住他们可能会评估的数以千计的时间，并可能会影响您的页面的性能。

If you must use CSS expressions, remember that they may be evaluated thousands of times and could affect the performance of your page.

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第4步：评估正则表达式。

Step 4: Evaluate the regular expression.

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So the take away is that if the user actually gives me two or three or four or whatever, this is this expression "is n less than 1" is going to evaluate to false if it's actually two or three or four or whatever.

所以先不管用户实际上给我,3，4还是其他数，这个表达式,“是否n小于1“将被评估为错误的,如果输入额是2，3，4或其它的数。

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