I have a string, var str = "Runner, The (1999)";
Using substr(), I need to see if ", The" is contained in str starting from 7 characters back, then if it is, remove those characters and put them in the start. Something like this:
if (str.substr(-7) === ', The') // If str has ', The' starting from 7 characters back...
{
str = 'The ' + str.substr(-7, 5); // Add 'The ' to the start of str and remove it from middle.
}
The resulting str should equal "The Runner (1999)"
Please, no regular expressions or other functions. I'm trying to learn how to use substr.
var str = "Runner, The (1999)";
if(str.indexOf(", The") != -1) {
str = "The "+str.replace(", The","");
}
Here you go, using only substr
as requested:
var str = "Runner, The (1999)";
if(str.substr(-12, 5) === ', The') {
str = 'The ' + str.substr(0, str.length - 12) + str.substr(-7);
}
alert(str);
It should be noted that this is not the best way to achieve what you want (especially using hardcoded values like -7
– almost never as good as using things like lastIndexOf
, regex, etc). But you wanted substr
, so there it is.
If you want to use just substr:
var a = "Runner, The (1999)"
var newStr;
if (str.substr(-7) === ', The')
newStr= 'The ' +a.substr(0,a.length-a.indexOf('The')-4) + a.substr(a.indexOf('The')+3)
Use a.substr(0,a.length-a.indexOf('The')-4)
to obtain the words before "The" and a.substr(a.indexOf('The')+3)
to obtain the words after it.
So, you say that the solution should be limited to only substr method. There will be different solutions depending on what you mean by:
", The" is contained in str starting from 7 characters back
If you mean that it's found exactly in -7 position, then the code could look like this (I replaced -7 with -12, so that the code returned true):
function one() {
var a = "Runner, The (1999)";
var b = ", The";
var c = a.substr(-12, b.length);
if (c == b) {
a = "The " + a.substr(0, a.length - 12) +
a.substr(a.length - 12 + b.length);
}
}
If, however, substring ", The" can be found anywhere between position -7 and the end of the string, and you really need to use only substr, then check this out:
function two() {
var a = "Runner, The (1999)";
var b = ", The";
for (var i = a.length - 12; i < a.length - b.length; i++) {
if (a.substr(i, b.length) == b) {
a = "The " + a.substr(0, i) + a.substr(i + b.length);
break;
}
}
}
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