PHP's strspn in TypeScript

How to use

Install via yarn add locutus and import: import { strspn } from 'locutus/php/strings/strspn'.

Or with CommonJS: const { strspn } = require('locutus/php/strings/strspn')

Use a bundler that supports tree-shaking so you only ship the functions you actually use. Vite, webpack, Rollup, and Parcel all handle this. For server-side use this is less of a concern.

Examples

These examples are extracted from test cases that automatically verify our functions against their native counterparts.

#	code	expected result
1	strspn('42 is the answer, what is the question ...', '1234567890')	2
2	strspn('foo', 'o', 1, 2)	2

Here's what our current TypeScript equivalent to PHP's strspn looks like.

TSTypeScript JSJavaScript TSStandalone TS JSStandalone JS

Copy code

export function strspn(str1: string, str2: string, start?: number, lgth?: number): number {
  //      discuss at: https://locutus.io/php/strspn/
  // parity verified: PHP 8.3
  //     original by: Valentina De Rosa
  //     improved by: Brett Zamir (https://brett-zamir.me)
  //       example 1: strspn('42 is the answer, what is the question ...', '1234567890')
  //       returns 1: 2
  //       example 2: strspn('foo', 'o', 1, 2)
  //       returns 2: 2

  let found
  let stri
  let strj
  let j = 0
  let i = 0

  start = start ? (start < 0 ? str1.length + start : start) : 0
  lgth = lgth ? (lgth < 0 ? str1.length + lgth - start : lgth) : str1.length - start
  str1 = str1.substr(start, lgth)

  for (i = 0; i < str1.length; i++) {
    found = 0
    stri = str1.substring(i, i + 1)
    for (j = 0; j <= str2.length; j++) {
      strj = str2.substring(j, j + 1)
      if (stri === strj) {
        found = 1
        break
      }
    }
    if (found !== 1) {
      return i
    }
  }

  return i
}

export function strspn(str1, str2, start, lgth) {
  //      discuss at: https://locutus.io/php/strspn/
  // parity verified: PHP 8.3
  //     original by: Valentina De Rosa
  //     improved by: Brett Zamir (https://brett-zamir.me)
  //       example 1: strspn('42 is the answer, what is the question ...', '1234567890')
  //       returns 1: 2
  //       example 2: strspn('foo', 'o', 1, 2)
  //       returns 2: 2

  let found
  let stri
  let strj
  let j = 0
  let i = 0

  start = start ? (start < 0 ? str1.length + start : start) : 0
  lgth = lgth ? (lgth < 0 ? str1.length + lgth - start : lgth) : str1.length - start
  str1 = str1.substr(start, lgth)

  for (i = 0; i < str1.length; i++) {
    found = 0
    stri = str1.substring(i, i + 1)
    for (j = 0; j <= str2.length; j++) {
      strj = str2.substring(j, j + 1)
      if (stri === strj) {
        found = 1
        break
      }
    }
    if (found !== 1) {
      return i
    }
  }

  return i
}

Improve this function

Locutus is a community effort following The McDonald's Theory: we ship first iterations, hoping others will improve them. If you see something that could be better, we'd love your contribution.

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