[英]What is Passed to the JavaScript replace() Function?
I've seen str.replace(..., ...)
passed a function for its second argument. 我已经看到
str.replace(..., ...)
为第二个参数传递了一个函数。 What is passed to the function? 什么传递给函数? It goes like this:
它是这样的:
"string_test".replace(/(.*)_(.*)/, function(a, b) { return a + b; } )
How do you get it to pass the matched groups to the function? 如何获得将匹配的组传递给函数的信息? What are
a
and b
in this case if anything? 在这种情况下,
a
和b
是什么? I've been getting undefined
. 我一直
undefined
。
The first argument is the entirety of a match, and the rest represent the matched groups. 第一个参数是整个匹配项,其余参数代表匹配的组。 Basically it's like the array returned from
.match()
. 基本上就像从
.match()
返回的数组。
If the regex has the "g" modifier, then obviously the function is called over and over again. 如果正则表达式具有“ g”修饰符,则显然该函数会被反复调用。
Example: 例:
var s = "hello out there";
s.replace(/(\w*) *out (\w*)/, function(complete, first, second) {
alert(complete + " - " + first + " - " + second);
// hello out there - hello - there
});
edit — in the function, if you want the matched groups as an array, you can do: 编辑 -在函数中,如果要将匹配的组作为数组,则可以执行以下操作:
s.replace(/(\w*) *out (\w*)/, function(complete, first, second) {
var matches = [].slice.call(arguments, 0);
alert(matches[0] + " - " + matches[1] + " - " + matches[2]);
// hello out there - hello - there
});
Of course, as I wrote above that's what you get from the .match()
method too. 当然,正如我上面所写,这也是从
.match()
方法获得的。
我真的不想复制MDN文档及其说明: 将函数指定为参数
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