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JavaScript: parseInt() function

Description

The parseInt is used to get a numeric value from a string. parseInt is a top-level function and is not associated with any object.

Syntax

parseInt(numString, radix)

Parameters

numString: Required. A string that represents the value to test.

radix: Optional. An integer that represents the radix of the return value. A value between 2 and 36 indicating the base of the number contained in numString. For example, a radix of ten indicates to convert to a decimal number, eight octal, sixteen hexadecimal, and so on.

Example of parseInt() function

The following example shows how to use the parseInt() function.

JavaScript Code:

console.log('"21" -> '+parseInt("21"));
console.log('"21.42" -> '+parseInt("21.42"));
console.log('"100 234 54" -> '+parseInt("100 234 54"));
console.log('"89 Math" ->'+parseInt("89 Math"));
console.log('"Math 89" ->'+parseInt("Math 89"));
console.log();
console.log(parseInt("100",10));
console.log(parseInt("001"));
console.log(parseInt("100",8));
console.log(parseInt("0x10"));
console.log(parseInt("10",16));

View the example in the browser

Live demo:

See the Pen parselnt-function-1 by w3resource (@w3resource) on CodePen.

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JavaScript: Tips of the Day

Returns all unique values of an array, based on a provided comparator function

Example:

const tips_uniqueElementsBy = (arr, fn) =>
  arr.reduce((acc, v) => {
    if (!acc.some(x => fn(v, x))) acc.push(v);
    return acc;
  }, []);

console.log(tips_uniqueElementsBy(
  [
    { id: 0, value: 'p' },
    { id: 1, value: 'q' },
    { id: 2, value: 'r' },
    { id: 1, value: 's' },
    { id: 0, value: 't' }
  ],
  (a, b) => a.id == b.id
)); 

Output:

[[object Object] {
  id: 0,
  value: "p"
}, [object Object] {
  id: 1,
  value: "q"
}, [object Object] {
  id: 2,
  value: "r"
}]