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In-depth understanding of the analysis of REGEXP objects in JS regular expressions
In-depth understanding of the analysis of REGEXP objects in JS regular expressions
这篇文章主要介绍了关于深入理解JS正则表达式之REGEXP对象的解析，有着一定的参考价值，现在分享给大家，有需要的朋友可以参考一下
REGEXP对象
JavaScript通过内置对象RegExp支持正则表达式，有两种方法实例化RegExp对象。
1.字面量
2.构造函数
字面量
字面量是直接通过/.../创建RegExp对象实例。
var reg = /\bis\b/ var text = 'He is a boy.' var result = text.replace(reg, 'IS') // 'He IS a boy.'
构造函数
构造函数版本看起来比较像Java中创建实例的样子，但是正如不推荐使用new Array而是使用[]创建数组一样，推荐使用字面量创建RegExp对象实例。
var reg = new RegExp('\\bis\\b', 'g') var text = 'He is a boy. It is a dog' var result = text.replace(reg, 'IS') // 'He IS a boy. It IS a dog'
修饰符
在正常情况下，正则匹配到第一个匹配项则停止，并且默认大小写敏感，如果想修改默认选项，则需要修饰符。值得一提，修饰符可以同时使用，比如我想要全局大小写不敏感，则同时在正则末尾加上gi
g：global 全文搜索
i：ignore case 忽略大小写
m：multiple lines 多行搜索
var reg = /\bis\b/gi var text = 'He is a boy. It Is a dog' var result = text.replace(reg, 0) // 'He 0 a boy. It 0 a dog'
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