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📄 getContextualType.ts

📊 Analysis Summary

Metric	Count
🔧 Functions	1
📊 Variables & Constants	1

📚 Table of Contents

• Variables & Constants
• Functions

🛠️ File Location:

📂 packages/type-utils/src/getContextualType.ts

Variables & Constants

Name	Type	Kind	Value	Exported
parent	any	const	node.parent	✗

---

Functions

getContextualType(checker: ts.TypeChecker, node: ts.Expression): ts.Type | undefined

Code

export function getContextualType(
  checker: ts.TypeChecker,
  node: ts.Expression,
): ts.Type | undefined {
  const parent = node.parent;

  if (ts.isCallExpression(parent) || ts.isNewExpression(parent)) {
    if (node === parent.expression) {
      // is the callee, so has no contextual type
      return;
    }
  } else if (
    ts.isVariableDeclaration(parent) ||
    ts.isPropertyDeclaration(parent) ||
    ts.isParameter(parent)
  ) {
    return parent.type ? checker.getTypeFromTypeNode(parent.type) : undefined;
  } else if (ts.isJsxExpression(parent)) {
    return checker.getContextualType(parent);
  } else if (
    ts.isIdentifier(node) &&
    (ts.isPropertyAssignment(parent) ||
      ts.isShorthandPropertyAssignment(parent))
  ) {
    return checker.getContextualType(node);
  } else if (
    ts.isBinaryExpression(parent) &&
    parent.operatorToken.kind === ts.SyntaxKind.EqualsToken &&
    parent.right === node
  ) {
    // is RHS of assignment
    return checker.getTypeAtLocation(parent.left);
  } else if (
    ![ts.SyntaxKind.JsxExpression, ts.SyntaxKind.TemplateSpan].includes(
      parent.kind,
    )
  ) {
    // parent is not something we know we can get the contextual type of
    return;
  }
  // TODO - support return statement checking

  return checker.getContextualType(node);
}

• JSDoc:

  /**
   * Returns the contextual type of a given node.
   * Contextual type is the type of the target the node is going into.
   * i.e. the type of a called function's parameter, or the defined type of a variable declaration
   */
  

• Parameters:

• checker: ts.TypeChecker
• node: ts.Expression
• Return Type: ts.Type | undefined
• Calls:
• ts.isCallExpression
• ts.isNewExpression
• ts.isVariableDeclaration
• ts.isPropertyDeclaration
• ts.isParameter
• checker.getTypeFromTypeNode
• ts.isJsxExpression
• checker.getContextualType
• ts.isIdentifier
• ts.isPropertyAssignment
• ts.isShorthandPropertyAssignment
• ts.isBinaryExpression
• checker.getTypeAtLocation
• [ts.SyntaxKind.JsxExpression, ts.SyntaxKind.TemplateSpan].includes
• Internal Comments:

  // is the callee, so has no contextual type
  // is RHS of assignment
  // parent is not something we know we can get the contextual type of
  // TODO - support return statement checking
  

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