在Javascript中，如何在字符串中查找字符并将所有字符放在变量前

Question

In javascript, I am trying to make a program that had to do with fractions that you can input and I need a function that will convert a fraction in this format( "10/27") to either 10 or 27 depending on user specification but I don't know how I would code this function. Any code or suggestions to get me started would be much appreciated.

Answer 1

Considering str contains the input value then,

a = str.substring(str.indexOf("/")+1);
b = str.substring(0, str.indexOf("/"));

Output: if str is "10/17" then,

a == 17;
b == 10;

Answer 2

You can split the string into an array with split() , then take the first or second part as the numerator or denominator:

function getNumerator(fraction) {
    // fraction = "10/27"
    return fraction.split("/")[0];
}

function getDenominator(fraction) {
    // fraction = "10/27"
    return fraction.split("/")[1];
}

Answer 3

var fraction = "10/27".split("/");
var numerator = fraction[0];
var denominator = fraction[1];

You can of course use a library for it too: https://github.com/ekg/fraction.js

With this library the answer would be:

(new Fraction(10, 27)).numerator

Answer 4

You can search in string using indexOf() . It returns first position of searched string.

If you want to split string using a character in it, use split() . It will return an array. So for eg: in you string 27/10 , indexOf / is 3 but if you do split, you will get array of 2 values, 27 and 10.

 function splitString(str, searchStr) { return str.split(searchStr); } function calculateValue(str) { var searchStr = '/'; var values = splitString(str, searchStr); var result = parseInt(values[0]) / parseInt(values[1]); notify(str, result); } function notify(str, result) { console.log(result); document.getElementById("lblExpression").innerText = str; document.getElementById("lblResult").innerText = result; } (function() { var str = "27/10"; calculateValue(str) })() 

 Expression: <p id="lblExpression"></p> Result: <p id="lblResult"></p>