parse() — tailwindcss Function Reference

Source Code

packages/tailwindcss/src/attribute-selector-parser.ts lines 35–216

export function parse(input: string): AttributeSelector | null {
  // Must start with `[` and end with `]`
  if (input[0] !== '[' || input[input.length - 1] !== ']') {
    return null
  }

  let i = 1
  let start = i
  let end = input.length - 1

  // Skip whitespace, e.g.: [   data-foo]
  //                         ^^^
  while (isAsciiWhitespace(input.charCodeAt(i))) i++

  // Attribute name, e.g.: [data-foo]
  //                        ^^^^^^^^
  {
    start = i
    for (; i < end; i++) {
      let currentChar = input.charCodeAt(i)
      // Skip escaped character
      if (currentChar === BACKSLASH) {
        i++
        continue
      }
      if (currentChar >= UPPER_A && currentChar <= UPPER_Z) continue
      if (currentChar >= LOWER_A && currentChar <= LOWER_Z) continue
      if (currentChar >= ZERO && currentChar <= NINE) continue
      if (currentChar === DASH || currentChar === UNDERSCORE) continue
      break
    }

    // Must have at least one character in the attribute name
    if (start === i) {
      return null
    }
  }
  let attribute = input.slice(start, i)

  // Skip whitespace, e.g.: [data-foo   =value]
  //                                 ^^^
  while (isAsciiWhitespace(input.charCodeAt(i))) i++

  // At the end, e.g.: `[data-foo]`
  if (i === end) {
    return {
      attribute,
      operator: null,
      quote: null,
      value: null,
      sensitivity: null,
    }
  }

  // Operator, e.g.: [data-foo*=value]
  //                          ^^
  let operator = null
  let currentChar = input.charCodeAt(i)
  if (currentChar === EQUALS) {
    operator = '='
    i++
  } else if (
    (currentChar === TILDE ||
      currentChar === PIPE ||
      currentChar === CARET ||
      currentChar === DOLLAR ||
      currentChar === ASTERISK) &&
    input.charCodeAt(i + 1) === EQUALS
  ) {
    operator = input[i] + '='
    i += 2
  } else {
    return null // Invalid operator
  }

  // Skip whitespace, e.g.: [data-foo*=   value]
  //                                   ^^^
  while (isAsciiWhitespace(input.charCodeAt(i))) i++

  // At the end, that means that we have an operator but no valid, which is
  // invalid, e.g.: `[data-foo*=]`