JavaScript: parseInt() function

Last update on May 28 2022 10:32:25 (UTC/GMT +8 hours)

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

How to insert an item into an array at a specific index (JavaScript)?

What you want is the splice function on the native array object.

arr.splice(index, 0, item); will insert item into arr at the specified index (deleting 0 items first, that is, it's just an insert). In this example we will create an array and add an element to it into index 2:

var arr = [];
arr[0] = "Jani";
arr[1] = "Hege";
arr[2] = "Stale";
arr[3] = "Kai Jim";
arr[4] = "Borge";

console.log(arr.join());
arr.splice(2, 0, "Lene");
console.log(arr.join());

Ref: https://bit.ly/2BXbp04