按指定字符数拆分JSON字符串的JavaScript代码报错：索引与长度需指向字符串内有效位置

Let's break down why your code is throwing that error and fix it step by step.

What's Causing the Error? #

1. Case-sensitive variable mismatches: You're passing nCharacters and valueDeinfo to the function, but the function expects nCharacter and valueDeInfo (note the capitalization differences). This can lead to incorrect length values or undefined strings being passed in.
2. Backwards logic for the final chunk: In your loop, you're slicing the string first before updating the end value to the actual string length. If your string isn't a perfect multiple of 4000 characters, this means you're trying to slice beyond the string's bounds (especially if you're using a .NET-based JS environment like JScript.NET, which enforces strict index bounds).
3. Unnecessary manual tracking of begin/end: Your current approach to updating these variables is error-prone and easy to mess up.
4. Array access oversight: Your valueDeInfo is an array containing a single JSON string, but you're treating it like the string itself, which leads to incorrect length calculations.

Corrected Code #

Here's a cleaned-up, working version of your function with fixes for all the above issues:

var splitA = [];

function separatedFields(totalLength, targetString) {
  const chunkSize = 4000;
  const chunks = [];
  const totalChunks = Math.ceil(totalLength / chunkSize);

  for (let i = 0; i < totalChunks; i++) {
    const start = i * chunkSize;
    // Ensure we never go beyond the actual string length
    const end = Math.min(start + chunkSize, totalLength);
    chunks.push(targetString.slice(start, end));
  }

  return chunks;
}

// Fix variable capitalization and access the actual string inside the array
const valueDeInfo = ['{"Status":"OK","RequestID":"e5517d4e-ee43-451a-bbe8-09f9fc714c21","Results":[{"CustomerKey":null,"Name":"Control","ObjectID":null,"FieldType":"Number","IsPrimaryKey":false,"MaxLength":0,"Ordinal":3,"DefaultValue":"1","DataExtension":null,"StorageType":"Unspecified","DataType":null,"ValueType":"xsdstring","PropertyType":"string","IsCreatable":false,"IsUpdatable":false,"IsRetrievable":false,"IsQueryable":false,"IsFilterable":false,"IsPartnerProperty":false,"IsAccountProperty":false,"PartnerMap":null,"AttributeMaps":null,"Markups":null,"Precision":0,"Scale":0,"Label":null,"Description":null,"MinLength":0,"MinValue":null,"MaxValue":null,"IsRequired":false,"IsViewable":false,"IsEditable":false,"IsNillable":false,"IsRestrictedPicklist":false,"PicklistItems":null,"IsSendTime":false,"DisplayOrder":0,"References":null,"RelationshipName":null,"Status":null,"IsContextSpecific":false,"Client":null,"PartnerKey":null,"PartnerProperties":null,"CreatedDate":"0001-01-01T00:00:00.000","ModifiedDate":null,"ID":0,"Owner":null,"CorrelationID":null,"ObjectState":null,"IsPlatformObject":false}, {"CustomerKey":null,"Name":"CategoryID","ObjectID":null,"FieldType":"Number","IsPrimaryKey":false,"MaxLength":0,"Ordinal":8,"DefaultValue":"","DataExtension":null,"StorageType":"Unspecified","DataType":null,"ValueType":"xsdstring","PropertyType":"string","IsCreatable":false,"IsUpdatable":false,"IsRetrievable":false,"IsQueryable":false,"IsFilterable":false,"IsPartnerProperty":false,"IsAccountProperty":false,"PartnerMap":null,"AttributeMaps":null,"Markups":null,"Precision":0,"Scale":0,"Label":null,"Description":null,"MinLength":0,"MinValue":null,"MaxValue":null,"IsRequired":false,"IsViewable":false,"IsEditable":false,"IsNillable":false,"IsRestrictedPicklist":false,"PicklistItems":null,"IsSendTime":false,"DisplayOrder":0,"References":null,"RelationshipName":null,"Status":null,"IsContextSpecific":false,"Client":null,"PartnerKey":null,"PartnerProperties":null,"CreatedDate":"0001-01-01T00:00:00.000","ModifiedDate":null,"ID":0,"Owner":null,"CorrelationID":null,"ObjectState":null,"IsPlatformObject":false}, {"CustomerKey":null,"Name":"IsSendable","ObjectID":null,"FieldType":"Boolean","IsPrimaryKey":false,"MaxLength":0,"Ordinal":2,"DefaultValue":"","DataExtension":null,"StorageType":"Unspecified","DataType":null,"ValueType":"xsdstring","PropertyType":"string","IsCreatable":false,"IsUpdatable":false,"IsRetrievable":false,"IsQueryable":false,"IsFilterable":false,"IsPartnerProperty":false,"IsAccountProperty":false,"PartnerMap":null,"AttributeMaps":null,"Markups":null,"Precision":0,"Scale":0,"Label":null,"Description":null,"MinLength":0,"MinValue":null,"MaxValue":null,"IsRequired":false,"IsViewable":false,"IsEditable":false,"IsNillable":false,"IsRestrictedPicklist":false,"PicklistItems":null,"IsSendTime":false,"DisplayOrder":0,"References":null,"RelationshipName":null,"Status":null,"IsContextSpecific":false,"Client":null,"PartnerKey":null,"PartnerProperties":null,"CreatedDate":"0001-01-01T00:00:00.000","ModifiedDate":null,"ID":0,"Owner":null,"CorrelationID":null,"ObjectState":null,"IsPlatformObject":false}, {"CustomerKey":null,"Name":"Name","ObjectID":null,"FieldType":"Text","IsPrimaryKey":true,"MaxLength":50,"Ordinal":0,"DefaultValue":"","DataExtension":null,"StorageType":"Unspecified","DataType":null,"ValueType":"xsdstring","PropertyType":"string","IsCreatable":false,"IsUpdatable":false,"IsRetrievable":false,"IsQueryable":false,"IsFilterable":false,"IsPartnerProperty":false,"IsAccountProperty":false,"PartnerMap":null,"AttributeMaps":null,"Markups":null,"Precision":0,"Scale":0,"Label":null,"Description":null,"MinLength":0,"MinValue":null,"MaxValue":null,"IsRequired":true,"IsViewable":false,"IsEditable":false,"IsNillable":false,"IsRestrictedPicklist":false,"PicklistItems":null,"IsSendTime":false,"DisplayOrder":0,"References":null,"RelationshipName":null,"Status":null,"IsContextSpecific":false,"Client":null,"PartnerKey":null,"PartnerProperties":null,"CreatedDate":"0001-01-01T00:00:00.000","ModifiedDate":null,"ID":0,"Owner":null,"CorrelationID":null,"ObjectState":null,"IsPlatformObject":false}, {"CustomerKey":null,"Name":"IsRequired","ObjectID":null,"FieldType":"Boolean","IsPrimaryKey":false,"MaxLength":0,"Ordinal":10,"DefaultValue":"","DataExtension":null,"StorageType":"Unspecified","DataType":null,"ValueType":"xsdstring","PropertyType":"string","IsCreatable":false,"IsUpdatable":false,"IsRetrievable":false,"IsQueryable":false,"IsFilterable":false,"IsPartnerProperty":false,"IsAccountProperty":false,"PartnerMap":null,"AttributeMaps":null,"Markups":null,"Precision":0,"Scale":0,"Label":null,"Description":null,"MinLength":0,"MinValue":null,"MaxValue":null,"IsRequired":false,"IsViewable":false,"IsEditable":false,"IsNillable":false,"IsRestrictedPicklist":false,"PicklistItems":null,"IsSendTime":false,"DisplayOrder":0,"References":null,"RelationshipName":null,"Status":null,"IsContextSpecific":false,"Client":null,"PartnerKey":null,"PartnerProperties":null,"CreatedDate":"0001-01-01T00:00:00.000","ModifiedDate":null,"ID":0,"Owner":null,"CorrelationID":null,"ObjectState":null,"IsPlatformObject":false}, {"CustomerKey":null,"Name":"infoDE3","ObjectID":null,"FieldType":"Text","IsPrimaryKey":false,"MaxLength":4000,"Ordinal":18,"DefaultValue":"","DataExtension":null,"StorageType":"Unspecified","DataType":null,"ValueType":"xsdstring","PropertyType":"string","IsCreatable":false,"IsUpdatable":false,"IsRetrievable":false,"IsQueryable":false,"IsFilterable":false,"IsPartnerProperty":false,"IsAccountProperty":false,"PartnerMap":null,"AttributeMaps":null,"Markups":null,"Precision":0,"Scale":0,"Label":null,"Description":null,"MinLength":0,"MinValue":null,"MaxValue":null,"IsRequired":true,"IsViewable":false,"IsEditable":false,"IsNillable":false,"IsRestrictedPicklist":false,"PicklistItems":null,"IsSendTime":false,"DisplayOrder":0,"References":null,"RelationshipName":null,"Status":null,"IsContextSpecific":false,"Client":null,"PartnerKey":null,"PartnerProperties":null,"CreatedDate":"0001-01-01T00:00:00.000","ModifiedDate":null,"ID":0,"Owner":null,"CorrelationID":null,"ObjectState":null,"IsPlatformObject":false}, {"CustomerKey":null,"Name":"Description","ObjectID":null,"FieldType":"Text","IsPrimaryKey":false,"MaxLength":4000,"Ordinal":6,"DefaultValue":"","DataExtension":null,"StorageType":"Unspecified","DataType":null,"ValueType":"xsdstring","PropertyType":"string","IsCreatable":false,"IsUpdatable":false,"IsRetrievable":false,"IsQueryable":false,"IsFilterable":false,"IsPartnerProperty":false,"IsAccountProperty":false,"PartnerMap":null,"AttributeMaps":null,"Markups":null,"Precision":0,"Scale":0,"Label":null,"Description":null,"MinLength":0,"MinValue":null,"MaxValue":null,"IsRequired":false,"IsViewable":false,"IsEditable":false,"IsNillable":false,"IsRestrictedPicklist":false,"PicklistItems":null,"IsSendTime":false,"DisplayOrder":0,"References":null,"RelationshipName":null,"Status":null,"IsContextSpecific":false,"Client":null,"PartnerKey":null,"PartnerProperties":null,"CreatedDate":"0001-01-01T00:00:00.000","ModifiedDate":null,"ID":0,"Owner":null,"CorrelationID":null,"ObjectState":null,"IsPlatformObject":false}, {"CustomerKey":null,"Name":"ModifiedDate","ObjectID":null,"FieldType":"Date","IsPrimaryKey":false,"MaxLength":0,"Ordinal":7,"DefaultValue":"","DataExtension":null,"StorageType":"Unspecified","DataType":null,"ValueType":"xsdstring","PropertyType":"string","IsCreatable":false,"IsUpdatable":false,"IsRetrievable":false,"IsQueryable":false,"IsFilterable":false,"IsPartnerProperty":false,"IsAccountProperty":false,"PartnerMap":null,"AttributeMaps":null,"Markups":null,"Precision":0,"Scale":0,"Label":null,"Description":null,"MinLength":0,"MinValue":null,"MaxValue":null,"IsRequired":false,"IsViewable":false,"IsEditable":false,"IsNillable":false,"IsRestrictedPicklist":false,"PicklistItems":null,"IsSendTime":false,"DisplayOrder":0,"References":null,"RelationshipName":null,"Status":null,"IsContextSpecific":false,"Client":null,"PartnerKey":null,"PartnerProperties":null,"CreatedDate":"0001-01-01T00:00:00.000","ModifiedDate":null,"ID":0,"Owner":null,"CorrelationID":null,"ObjectState":null,"IsPlatformObject":false}'];
const totalLength = valueDeInfo[0].length; // Get length of the actual JSON string, not the array
splitA = separatedFields(totalLength, valueDeInfo[0]);
Write("ARRAY FIRST 4000: " + splitA[0]);

Key Improvements #

• Variable consistency: Fixed case mismatches so the function receives correct inputs.
• Safe slicing: Uses Math.min() to guarantee we never slice beyond the string's actual length, eliminating the index out-of-bounds error.
• Simplified logic: Calculates chunk start/end positions directly from the loop index, removing the need to manually track begin and end (which was the source of your final chunk bug).
• Array correction: Accesses valueDeInfo[0] since your original variable is an array containing a single JSON string, not the string itself.

内容的提问来源于stack exchange，提问作者Paullogon