46 lines
1.1 KiB
JavaScript
46 lines
1.1 KiB
JavaScript
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String.prototype.substr = function (start, length) {
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if (start === undefined) {
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return this.toString()
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}
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if (typeof start !== 'number' || (typeof length !== 'number' && length !== undefined) ) {
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return ''
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}
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const strArr = [...this]
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const _length = strArr.length
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if (_length + start < 0) {
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start = 0
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}
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if (length === undefined || (start < 0 && start + length > 0)) {
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return strArr.slice(start).join('')
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} else {
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return strArr.slice(start, start + length).join('')
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}
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}
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String.prototype.substring = function (start, end) {
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if (start === undefined) {
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return this.toString()
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}
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if (typeof start !== 'number' || (typeof end !== 'number' && end !== undefined) ) {
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return ''
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}
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if (!(start > 0)) {
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start = 0
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}
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if (!(end > 0) && end !== undefined) {
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end = 0
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}
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const strArr = [...this]
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const _length = strArr.length
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if (start > _length) {
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start = _length
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}
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if (end > _length) {
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end = _length
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}
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if (end < start) {
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[start, end] = [end, start]
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}
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return strArr.slice(start, end).join('')
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}
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