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Both substring and substr are used to extract parts of a string, but there are subtle differences between the substring() and substr() methods in terms of syntax and behavior.
1. substring(start, end)
- Parameters:
- start: The index to start extracting (inclusive).
- end: The index to stop extracting (exclusive).
- Behavior:
- If start > end, it swaps the arguments.
- Negative values are treated as 0.
1let str = "Hello World";
2 console.log(str.substring(0, 5)); // "Hello"
3 console.log(str.substring(5, 0)); // "Hello" (swapped)
4 console.log(str.substring(-3, 4)); // "Hell" (negative = 0)2. substr(start, length) _(Deprecated)_
- Parameters:
- start: The index to start extracting.
- length: The number of characters to extract.
- Behavior:
- If start is negative, it counts from the end of the string.
- If length is omitted, it extracts to the end of the string.
1let str = "Hello World"; console.log(str.substr(0, 5)); // "Hello"
2 console.log(str.substr(-5, 3)); // "Wor" (starts from 'W')`Note: substr() is considered a legacy feature in ECMAScript, so it is best to avoid using it if possible.
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JavaScript Coding Exercise 42
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