zoukankan      html  css  js  c++  java
  • javascript convert str to number

     Converting Strings to Numbers

    Table of ContentsTable of Contents

    Question: How do I convert strings to numbers in JavaScript?

    Answer: To convert a string to a number, use the JavaScript function parseFloat (for conversion to a floating-point number) or parseInt (for conversion to an integer).

    parseFloat syntax:   parseFloat('string')

    How it works:
    The argument of parseFloat must be a string or a string expression. The result of parseFloat is the number whose decimal representation was contained in that string (or the number found in the beginning of the string). If the string argument cannot be parsed as a decimal number, the results will be different in different browsers (either 0 or NaN).

    Examples (comments in each line give the conversion results):

    parseFloat('1.45kg')  // 1.45
    parseFloat('77.3')    // 77.3
    parseFloat('077.3')   // 77.3
    parseFloat('0x77.3')  // 0
    parseFloat('.3')      // 0.3
    parseFloat('0.1e6')   // 100000
    

    parseInt syntax:   parseInt( 'string' [, base] )

    How it works:
    The first argument of parseInt must be a string or a string expression. The result returned by parseInt is an integer whose representation was contained in that string (or the integer found in the beginning of the string). The second argument (base), if present, specifies the base (radix) of the number whose string representation is contained in the string. The base argument can be any integer from 2 to 36.

    If there is only one argument, the number base is detected according to the general JavaScript syntax for numbers. Strings that begin with 0x or -0x are parsed as hexadecimals; strings that begin with 0 or -0 are parsed as octal numbers. All other strings are parsed as decimal numbers.

    If the string argument cannot be parsed as an integer, the results will be different in different browsers (either 0 or NaN).

    Examples (comments in each line give the conversion results):

    parseInt('123.45')  // 123
    parseInt('77')      // 77
    parseInt('077',10)  // 77
    parseInt('77',8)    // 63  (= 7 + 7*8)
    parseInt('077')     // 63  (= 7 + 7*8)
    parseInt('77',16)   // 119 (= 7 + 7*16)
    parseInt('0x77')    // 119 (= 7 + 7*16)
    parseInt('099')     // 0 (9 is not an octal digit)
    parseInt('99',8)    // 0 or NaN, depending on the platform
    parseInt('0.1e6')   // 0
    parseInt('ZZ',36)   // 1295 (= 35 + 35*36)
    

    Copyright © 1999-2011, JavaScripter.net

  • 相关阅读:
    装饰器 、迭代器,json,pickle,hash
    装饰器知识
    python 编码问题处理
    大数据组件服务的启动与关闭命令
    网站数据统计分析之一:日志收集原理及其实现
    style资源搜索
    分享5个超实用的办公资源网站,错过就可惜了!
    资源搜索
    七大顶级资源
    hive工具bin下的schematool的作用
  • 原文地址:https://www.cnblogs.com/lexus/p/1877936.html
Copyright © 2011-2022 走看看