42 lines
1.3 KiB
JavaScript
42 lines
1.3 KiB
JavaScript
/*
|
|
We don't want to include babel-polyfill in our project.
|
|
- Library authors should be using babel-runtime for non-global polyfilling
|
|
- Adding babel-polyfill/-runtime increases bundle size significantly
|
|
|
|
We will include our polyfill instance methods as regular functions.
|
|
*/
|
|
|
|
export function startsWith(str, searchString, position) {
|
|
return str.substr(position || 0, searchString.length) === searchString
|
|
}
|
|
|
|
export function endsWith(str, searchString, position) {
|
|
const index = (position || str.length) - searchString.length
|
|
const lastIndex = str.lastIndexOf(searchString, index)
|
|
return lastIndex !== -1 && lastIndex === index
|
|
}
|
|
|
|
export function stringIncludes(str, searchString, position) {
|
|
return str.indexOf(searchString, position || 0) !== -1
|
|
}
|
|
|
|
export function isRealNaN(x) {
|
|
return typeof x === 'number' && isNaN(x)
|
|
}
|
|
|
|
export function arrayIncludes(array, searchElement, position) {
|
|
const len = array.length
|
|
if (len === 0) return false
|
|
|
|
const lookupIndex = position | 0
|
|
const isNaNElement = isRealNaN(searchElement)
|
|
let searchIndex = lookupIndex >= 0 ? lookupIndex : len + lookupIndex
|
|
while (searchIndex < len) {
|
|
const element = array[searchIndex++]
|
|
if (element === searchElement) return true
|
|
if (isNaNElement && isRealNaN(element)) return true
|
|
}
|
|
|
|
return false
|
|
}
|