javascript正则表达式在Chrome控制台中使用相同的表达式得到不同的答案

Question

我想在 Chrome 控制台中测试 Javascript Regex。然而，我用相同的表达得到不同的答案(参见图片)。如果我使用原始文字来测试，我可以得到正确的答案。这是什么原因呢？

re = /^[a-z][0-9a-z]*$/g;
console.log(re.test("a34"));
console.log(re.test("a34"));
console.log(re.test("a34"));
console.log(re.test("a34"));
console.log(/^[a-z][0-9a-z]*$/g.test("a23"));
console.log(/^[a-z][0-9a-z]*$/g.test("a23"));

Answer 1

直接来自docs :

Use test() whenever you want to know whether a pattern is found in a string. test() returns a boolean, unlike the String.prototype.search() method, which returns the index (or -1 if not found). To get more information (but with slower execution), use the exec() method (similar to the String.prototype.match() method). As with exec() (or in combination with it), test() called multiple times on the same global regular expression instance will advance past the previous match.