Exercise - Lookahead, Lookbehind, Lookaround

/jsRegex Panels/i

try see compare understand learn JavaScript Regular Expressions

1. Question - Match the coefficients
Word Wrap
Enter input string
x³ + x² + x + 1 3x² - 125x + 12 2x³ + 5x² + 8x - 15 6x² + 18 - 35x 12x³ + 95x² - 115
Question: Match all the coefficients of x²
Enter regex pattern
Exercise / Test Modeanswer
i - Ignore Case
g - Global Match
m - Multiline
s - Dot All
u - Unicode
y - Sticky
With lastIndex^?
x³ + x² + x + 1 3x² - 125x + 12 2x³ + 5x² + 8x - 15 6x² + 18 - 35x 12x³ + 95x² - 115
Question: Match all the constant values ie the terms without the variable part. No need to match the sign (+ / -) or spaces before or after those constants.
Enter regex pattern
Exercise / Test Modeanswer
i - Ignore Case
g - Global Match
m - Multiline
s - Dot All
u - Unicode
y - Sticky
With lastIndex^?
x³ + x² + x + 1 3x² - 125x + 12 2x³ + 5x² + 8x - 15 6x² + 18 - 35x 12x³ + 95x² - 115
2. Question - Match based on the presence of words.
Word Wrap
Enter input string
food drinks travel fishing trekking food travel trekking drinks fishing food drinks trekking fishing travel trekking drinks food travel fishing trekking food travel fishing drinks trekking fishing food drinks travel
Question Match the word drinks only if it is followed by the word 'travel' in any of the sentence?
Enter regex pattern
Exercise / Test Modeanswer
i - Ignore Case
g - Global Match
m - Multiline
s - Dot All
u - Unicode
y - Sticky
With lastIndex^?
food drinks travel fishing trekking food travel trekking drinks fishing food drinks trekking fishing travel trekking drinks food travel fishing trekking food travel fishing drinks trekking fishing food drinks travel
Question Match the word drinks only if it is followed immediately by the word 'travel' in any of the sentence?
Enter regex pattern
Exercise / Test Modeanswer
i - Ignore Case
g - Global Match
m - Multiline
s - Dot All
u - Unicode
y - Sticky
With lastIndex^?
food drinks travel fishing trekking food travel trekking drinks fishing food drinks trekking fishing travel trekking drinks food travel fishing trekking food travel fishing drinks trekking fishing food drinks travel
Question Match the word drinks only if it is not followed by the word 'travel' in any of the sentence?
Enter regex pattern
Exercise / Test Modeanswer
i - Ignore Case
g - Global Match
m - Multiline
s - Dot All
u - Unicode
y - Sticky
With lastIndex^?
food drinks travel fishing trekking food travel trekking drinks fishing food drinks trekking fishing travel trekking drinks food travel fishing trekking food travel fishing drinks trekking fishing food drinks travel
3. Question - Find and match the positive and negative numbers?
Word Wrap
Enter input string
10 -25 -35 45 -150 25 -35 -147 8 88 888 8888 -3 -33 -333 -333
Question Match all the positive numbers only. The regexp should not match the spaces before or after the number.
Enter regex pattern
Exercise / Test Modeanswer
i - Ignore Case
g - Global Match
m - Multiline
s - Dot All
u - Unicode
y - Sticky
With lastIndex^?
10 -25 -35 45 -150 25 -35 -147 8 88 888 8888 -3 -33 -333 -333
Question Match all the negative numbers only. The regexp should not
match the spaces before or after the number.
match the - sign (negative sign).
Enter regex pattern
Exercise / Test Modeanswer
i - Ignore Case
g - Global Match
m - Multiline
s - Dot All
u - Unicode
y - Sticky
With lastIndex^?
10 -25 -35 45 -150 25 -35 -147 8 88 888 8888 -3 -33 -333 -333