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parseInt() function with example in JavaScript
JavaScript parseInt() function: Here, we are going to learn about the parseInt() function with example in JavaScript.
Submitted by IncludeHelp, on February 01, 2019
The function parseInt() is used to convert a string to the integer or we can say it can be used to parse a string and returns an integer.
Some of the points to remember:
- If a string contains number at the starting it can parse and returns the number.
- If a string contains alphabets at the starting and then the number, it cannot parse and returns "NaN".
- If a string contains leading and trailing spaces still function works and parse the string.
- As we have discussed in the post convert hexadecimal string to the decimal – parseInt() function parses the octal formatted value by passing base 8 and hexadecimal value by passing base 16 to the number.
Example:
<html>
<head>
<title>JavaScipt Example</title>
</head>
<body>
<script>
var str1 = "123"; //decoimal string
var str2 = "12.23"; //float string
var str3 = "123 456 789" //multiple Numbers
var str4 = " 123 "; //string contains leading & trailing spaces
var str5 = "012" ; //octal string
var str6 = "0x0A"; //hexadecimal string
var str7 = "123456 is my password"; //string contains Number in starting
var str8 = "My password is 123456"; //string contains Number in ending
//parsing & pritning the values
document.write("Number value of str1: " + parseInt(str1) + "<br>");
document.write("Number value of str2: " + parseInt(str2) + "<br>");
document.write("Number value of str3: " + parseInt(str3) + "<br>");
document.write("Number value of str4: " + parseInt(str4) + "<br>");
document.write("Number value of str5: " + parseInt(str5,8) + "<br>");
document.write("Number value of str6: " + parseInt(str6,16) + "<br>");
document.write("Number value of str7: " + parseInt(str7) + "<br>");
document.write("Number value of str8: " + parseInt(str8) + "<br>");
</script>
</body>
</html>
Output
Number value of str1: 123
Number value of str2: 12
Number value of str3: 123
Number value of str4: 123
Number value of str5: 10
Number value of str6: 10
Number value of str7: 123456
Number value of str8: NaN
JavaScript Built-in Functions »