JavaScript-在字符串匹配中使用变量

我发现了几个类似的问题，但没有帮助到我，所以我有这个问题:

var xxx = "victoria";
var yyy = "i";
alert(xxx.match(yyy/g).length);

我不知道如何在 match 命令中传递变量。请帮助。谢谢。

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xxx.match(yyy, 'g').length
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最佳答案

Although the match function doesn't accept string literals as regex patterns, you can use the constructor of the RegExp object and pass that to the String.match function:

var re = new RegExp(yyy, 'g');
xxx.match(re);

Any flags you need (such as /g) can go into the second parameter.

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You have to use RegExp object if your pattern is string

var xxx = "victoria";
var yyy = "i";
var rgxp = new RegExp(yyy, "g");
alert(xxx.match(rgxp).length);

If pattern is not dynamic string:

var xxx = "victoria";
var yyy = /i/g;
alert(xxx.match(yyy).length);
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for me anyways, it helps to see it used. just made this using the "re" example:

var analyte_data = 'sample-'+sample_id;
var storage_keys = $.jStorage.index();
var re = new RegExp( analyte_data,'g');
for(i=0;i<storage_keys.length;i++) {
if(storage_keys[i].match(re)) {
console.log(storage_keys[i]);
var partnum = storage_keys[i].split('-')[2];
}
}
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Example. To find number of vowels within the string

var word='Web Development Tutorial';
var vowels='[aeiou]';
var re = new RegExp(vowels, 'gi');
var arr = word.match(re);
document.write(arr.length);
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For example:

let myString = "Hello World"
let myMatch = myString.match(/H.*/)
console.log(myMatch)

Or

let myString = "Hello World"
let myVariable = "H"
let myReg = new RegExp(myVariable + ".*")
let myMatch = myString.match(myReg)
console.log(myMatch)
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Below is an example of a simple and effective way to mock 'like' operator in JS. enjoy!

const likePattern = '%%i%%%%%a';
const regexp = new RegExp(likePattern.replaceAll('%','.*'),"i");
console.log("victoria".match(regexp));


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