How Can I Count Character and String Occurrences and Validate String Length in JavaScript?

Determining Character and String Occurrences in a JavaScript String

Counting the frequency of specific characters or strings within a given string is a common programming task. In JavaScript, there are multiple approaches to achieve these counts.

Counting Character Occurrences

If you need to count the number of times a specific character appears within a string, you can use the match method. For instance, to count commas in the string mainStr = "str1,str2,str3,str4", you can use the match method with the regular expression /,/g:

console.log(("str1,str2,str3,str4".match(/,/g) || []).length); // logs 3

Counting String Occurrences

To count the number of substrings separated by a specific delimiter, you can use the split method. For example, to count the number of strings separated by commas in mainStr, you can use the split method with the comma as the delimiter:

console.log((mainStr.split(",").length)); // logs 4

Validating String Length

To validate the length of each substring in your string, you can use the length property. For instance, to ensure that the individual strings in mainStr do not exceed 15 characters, you can perform the following check:

const maxStringLength = 15;
const strings = mainStr.split(",");

for (let i = 0; i < strings.length; i++) {
  if (strings[i].length > maxStringLength) {
    console.error(`String ${strings[i]} exceeds the maximum length of ${maxStringLength}`);
  }
}

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