Website Structure

Frontend-Learner/node_modules/eslint-plugin-vue/lib/rules/no-negated-v-if-condition.js

@@ -0,0 +1,220 @@
+/**
+ * @author Wayne Zhang
+ * See LICENSE file in root directory for full license.
+ */
+'use strict'
+
+const utils = require('../utils')
+
+/**
+ * @typedef { VDirective & { value: (VExpressionContainer & { expression: Expression | null } ) | null  } } VIfDirective
+ */
+
+/**
+ * @param {Expression} expression
+ * @returns {boolean}
+ */
+function isNegatedExpression(expression) {
+  return (
+    (expression.type === 'UnaryExpression' && expression.operator === '!') ||
+    (expression.type === 'BinaryExpression' &&
+      (expression.operator === '!=' || expression.operator === '!=='))
+  )
+}
+
+/**
+ * @param {VElement} node
+ * @returns {VElement|null}
+ */
+function getNextSibling(node) {
+  if (!node.parent?.children) {
+    return null
+  }
+
+  const siblings = node.parent.children
+  const currentIndex = siblings.indexOf(node)
+
+  for (let i = currentIndex + 1; i < siblings.length; i++) {
+    const sibling = siblings[i]
+    if (sibling.type === 'VElement') {
+      return sibling
+    }
+  }
+
+  return null
+}
+
+/**
+ * @param {VElement} element
+ * @returns {boolean}
+ */
+function isDirectlyFollowedByElse(element) {
+  const nextElement = getNextSibling(element)
+  return nextElement ? utils.hasDirective(nextElement, 'else') : false
+}
+
+/**
+ * @param {VElement} element
+ */
+function getDirective(element) {
+  return /** @type {VIfDirective|undefined} */ (
+    element.startTag.attributes.find(
+      (attr) =>
+        attr.directive &&
+        attr.key.name &&
+        attr.key.name.name &&
+        ['if', 'else-if', 'else'].includes(attr.key.name.name)
+    )
+  )
+}
+
+module.exports = {
+  meta: {
+    type: 'suggestion',
+    docs: {
+      description: 'disallow negated conditions in v-if/v-else',
+      categories: undefined,
+      url: 'https://eslint.vuejs.org/rules/no-negated-v-if-condition.html'
+    },
+    fixable: null,
+    hasSuggestions: true,
+    schema: [],
+    messages: {
+      negatedCondition: 'Unexpected negated condition in v-if with v-else.',
+      fixNegatedCondition:
+        'Convert to positive condition and swap if/else blocks.'
+    }
+  },
+  /** @param {RuleContext} context */
+  create(context) {
+    const sourceCode = context.sourceCode
+
+    const processedPairs = new Set()
+
+    /**
+     * @param {Expression} expression
+     * @returns {string}
+     */
+    function getConvertedCondition(expression) {
+      if (
+        expression.type === 'UnaryExpression' &&
+        expression.operator === '!'
+      ) {
+        return sourceCode.text.slice(
+          expression.range[0] + 1,
+          expression.range[1]
+        )
+      }
+
+      if (expression.type === 'BinaryExpression') {
+        const left = sourceCode.getText(expression.left)
+        const right = sourceCode.getText(expression.right)
+
+        if (expression.operator === '!=') {
+          return `${left} == ${right}`
+        } else if (expression.operator === '!==') {
+          return `${left} === ${right}`
+        }
+      }
+
+      return sourceCode.getText(expression)
+    }
+
+    /**
+     * @param {VIfDirective} node
+     */
+    function checkNegatedCondition(node) {
+      if (!node.value?.expression) {
+        return
+      }
+
+      const expression = node.value.expression
+      const element = node.parent.parent
+
+      if (
+        !isNegatedExpression(expression) ||
+        !isDirectlyFollowedByElse(element)
+      ) {
+        return
+      }
+
+      const elseElement = getNextSibling(element)
+      if (!elseElement) {
+        return
+      }
+
+      const pairKey = `${element.range[0]}-${elseElement.range[0]}`
+      if (processedPairs.has(pairKey)) {
+        return
+      }
+      processedPairs.add(pairKey)
+
+      context.report({
+        node: expression,
+        messageId: 'negatedCondition',
+        suggest: [
+          {
+            messageId: 'fixNegatedCondition',
+            *fix(fixer) {
+              yield* swapElements(fixer, element, elseElement, expression)
+            }
+          }
+        ]
+      })
+    }
+
+    /**
+     * @param {RuleFixer} fixer
+     * @param {VElement} ifElement
+     * @param {VElement} elseElement
+     * @param {Expression} expression
+     */
+    function* swapElements(fixer, ifElement, elseElement, expression) {
+      const convertedCondition = getConvertedCondition(expression)
+
+      const ifDir = getDirective(ifElement)
+      const elseDir = getDirective(elseElement)
+
+      if (!ifDir || !elseDir) {
+        return
+      }
+
+      const ifDirectiveName = ifDir.key.name.name
+
+      const ifText = sourceCode.text.slice(
+        ifElement.range[0],
+        ifElement.range[1]
+      )
+      const elseText = sourceCode.text.slice(
+        elseElement.range[0],
+        elseElement.range[1]
+      )
+
+      const newIfDirective = `v-${ifDirectiveName}="${convertedCondition}"`
+      const newIfText =
+        elseText.slice(0, elseDir.range[0] - elseElement.range[0]) +
+        newIfDirective +
+        elseText.slice(elseDir.range[1] - elseElement.range[0])
+
+      const newElseDirective = 'v-else'
+      const newElseText =
+        ifText.slice(0, ifDir.range[0] - ifElement.range[0]) +
+        newElseDirective +
+        ifText.slice(ifDir.range[1] - ifElement.range[0])
+
+      yield fixer.replaceTextRange(ifElement.range, newIfText)
+      yield fixer.replaceTextRange(elseElement.range, newElseText)
+    }
+
+    return utils.defineTemplateBodyVisitor(context, {
+      /** @param {VIfDirective} node */
+      "VAttribute[directive=true][key.name.name='if']"(node) {
+        checkNegatedCondition(node)
+      },
+      /** @param {VIfDirective} node */
+      "VAttribute[directive=true][key.name.name='else-if']"(node) {
+        checkNegatedCondition(node)
+      }
+    })
+  }
+}