如何在javascript中匹配部分之后替换子字符串？

Question

I'd like to change everything after '=img' into something else, following code does not work:

var j = '/test/123=img?xyze'
j.replace(/=img\.*/, '');

Any idea how? Thanks,

AC

Answer 1

var j = '/test/123=img?xyze'
j=j.replace(/(=img)(.*)/, '$1_somethingElse');
console.log(j); //  "/test/123=img_somethingElse"

$1 is =img and the rest would be in $2 if you needed it.

Further reading: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/String/replace#Switching_words_in_a_string

Answer 2

Change to this:

var j = '/test/123=img?xyze';
var replacementText = 'something-else';
j = j.match(/^.+?=img/i)[0] + replacementText;

Otherwise, this little snippet below will give you all the parts of the query surrounding what you want to change, if you so desire:

var j = '/test/123=img?xyze';
var replacementText = 'something-else';
var parts = j.match(/^(.+?)(=img)(.+)$/i);

// /test/123=img?xyze : parts[0]
// /test/123          : parts[1]
// =img               : parts[2]
// ?xyze              : parts[3]

You would then do this for replacing:

j = parts[1] + parts[2] + replacementText;

Answer 3

 var j = '/test/123=img?xyze' var x = j.substr(0, j.indexOf('=img')) + '=img' console.log(x)